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* ZSH: (zsh).                     The Z Shell Manual.
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File: zsh.info,  Node: Completion System Configuration,  Next: Control Functions,  Prev: Initialization,  Up: Completion System

Completion System Configuration
===============================

This section gives a short overview of how the completion system works,
and then more detail on how users can configure how and when matches are
generated.

Overview
--------

When completion is attempted somewhere on the command line the
completion system first works out the context.  This takes account of a
number of things including the command word (such as `grep' or `zsh')
and options to which the current word may be an argument (such as the
`-o' option to zsh which takes a shell option as an argument).

This context information is condensed into a string consisting of
multiple fields separated by colons, referred to simply as `the context'
in the remainder of the documentation.  This is used to look up
_styles_, context-sensitive options that can be used to configure the
completion system.  The context used for lookup may vary during the same
call to the completion system.

The context string always consists of the following fields, separated
by colons and with a leading colon before the first:

   * The literal string completion, saying that this style is used by
     the completion system.  This distinguishes the context from those
     used by, for example, zle widgets and ZFTP functions.

   * The FUNCTION, if completion is called from a named widget rather
     than through the normal completion system.  Typically this is
     blank, but it is set by special widgets such as predict-on and the
     various functions in the Widget directory of the distribution to
     the name of that function, often in an abbreviated form.

   * The COMPLETER currently active, the name of the function without
     the leading underscore.  A `completer' is in overall control of
     how completion is to be performed; `complete' is the simplest, but
     other completers exist to perform related tasks such as
     correction, or to modify the behaviour of a later completer.  See
     *Note Control Functions:: for more information.

   * The COMMAND or a special -CONTEXT-, just at it appears following
     the #compdef tag or the compdef function.  Completion functions
     for commands that have sub-commands usually modify this field to
     contain the name of the command followed by a minus sign and the
     sub-command.  For example, the completion function for the cvs
     command sets this field to cvs-add when completing arguments to
     the add subcommand.

   * The ARGUMENT; this indicates which command line or option argument
     we are completing.  For command arguments this generally takes the
     form argument-N, where N is the number of the argument, and for
     arguments to options the form option-OPT-N where N is the number
     of the argument to option OPT.  However, this is only the case if
     the command line is parsed with standard UNIX-style options and
     arguments, so many completions do not set this.

   * The TAG.  Tags are used to discriminate between the types of
     matches a completion function can generate in a certain context and
     are described further below.


As an example, the context name

     :completion::complete:dvips:option-o-1:files

says that normal completion was attempted as the first argument to the
option -o of the command dvips:

     dvips -o ...

and the completion function will generate filenames.

Each type of completion the system can perform in a given context is
described by a `tag', a short descriptive string such as files in the
example above.  Any completion function may use any tag name it likes,
but a list of the more common ones is given below.

Usually completion will be tried by all possible tags in an order given
by the completion function.  However, this can be altered by using the
tag-order style.  Completion is then restricted to the list of given
tags in the given order.

The _complete_help bindable command shows all the contexts and tags
available for completion at a particular point.  This provides an easy
way of finding information for tag-order and other styles.  It is
described in *Note Bindable Commands::.

Styles determine such things as how the matches are generated, similarly
to shell options but with much more control.  They can have any number
of strings as their value.  They are defined with the zstyle builtin
command (*Note The zsh/zutil Module::).

When looking up styles the completion system uses full context names,
including the tag.  Looking up the value of a style therefore consists
of two things:  the context, which may be matched as a pattern, and the
name of the style itself, which must be given exactly.

For example, many completion functions can generate matches in a simple
and a verbose form and use the verbose style to decide which form
should be used.  To make all such functions use the verbose form, put

     zstyle ':completion:*' verbose yes

in a startup file (probably .zshrc).  This gives the verbose style the
value yes in every context inside the completion system, unless that
context has a more specific definition.  It is best to avoid giving the
context as `*' in case the style has some meaning outside the
completion system.

Many such general purpose styles can be configured simply by using the
compinstall function.

A more specific example of the use of the verbose style is by the
completion for the kill builtin.  If the style is set, the builtin
lists full job texts and process command lines; otherwise it shows the
bare job numbers and PIDs.  To turn the style off for this use only:

     zstyle ':completion:*:*:kill:*' verbose no

For even more control, the style can use one of the tags `jobs' or
`processes'.  To turn off verbose display only for jobs:

     zstyle ':completion:*:*:kill:*:jobs' verbose no

The -e option to zstyle even allows completion function code to appear
as the argument to a style; this requires some understanding of the
internals of completion functions (see *Note Completion Widgets::)).
For example:

     zstyle -e ':completion:*' completer '
         if [[ $words[1] = cvs ]]; then
           reply=(_complete)
         else
           reply=(_complete _approximate)
         fi'

uses the value `_complete' for the completer style in most contexts,
but the value `_complete _approximate' when the first word on the
command line is `cvs'.  This is probably more conveniently done by
specifying the style for two different contexts.  This form can be slow
and should be avoided for commonly examined styles such as menu and
list-rows-first.

Note that the order in which styles are _defined_ does not matter; the
style mechanism uses the most specific possible match for a particular
style to determine the set of values.  More precisely, strings are
preferred over patterns (for example, `:completion::complete:foo' is
more specific than `:completion::complete:*'), and longer patterns are
preferred over shorter patterns.

Style names like those of tags are arbitrary and depend on the
completion function.  However, the following two sections list some of
the most common tags and styles.

Standard Tags
-------------

Some of the following are only used when looking up particular styles
and do not refer to a type of match.

accounts
     used to look up the users-hosts style

all-expansions
     used by the _expand completer when adding the single string
     containing all possible expansions

all-files
     for the names of all files (as distinct from a particular subset,
     see the globbed-files tag).

arguments
     for arguments to a command

arrays
     for names of array parameters

association-keys
     for keys of associative arrays; used when completing inside a
     subscript to a parameter of this type

bookmarks
     when completing bookmarks (e.g. for URLs and the zftp function
     suite)

builtins
     for names of builtin commands

characters
     for single characters in arguments of commands such as stty.
     Also used when completing character classes after an opening
     bracket

colormapids
     for X colormap ids

colors
     for color names

commands
     for names of external commands.  Also used by complex commands
     such as cvs when completing names subcommands.

contexts
     for contexts in arguments to the zstyle builtin command

corrections
     used by the _approximate and _correct completers for possible
     corrections

cursors
     for cursor names used by X programs

default
     used in some contexts to provide a way of supplying a default when
     more specific tags are also valid.  Note that this tag is used
     when only the FUNCTION field of the context name is set

descriptions
     used when looking up the value of the format style to generate
     descriptions for types of matches

devices
     for names of device special files

directories
     for names of directories

directory-stack
     for entries in the directory stack

displays
     for X display names

domains
     for network domains

expansions
     used by the _expand completer for individual words (as opposed to
     the complete set of expansions) resulting from the expansion of a
     word on the command line

extensions
     for X server extensions

file-descriptors
     for numbers of open file descriptors

files
     the generic file-matching tag used by functions completing
     filenames

fonts
     for X font names

fstypes
     for file system types (e.g. for the mount command)

functions
     names of functions -- normally shell functions, although certain
     commands may understand other kinds of function

globbed-files
     for filenames when the name has been generated by pattern matching

groups
     for names of user groups

history-words
     for words from the history

hosts
     for hostnames

indexes
     for array indexes

jobs
     for jobs (as listed by the `jobs' builtin)

interfaces
     for network interfaces

keymaps
     for names of zsh keymaps

keysyms
     for names of X keysyms

libraries
     for names of system libraries

limits
     for system limits

local-directories
     for names of directories that are subdirectories of the current
     working directory when completing arguments of cd and related
     builtin commands (compare path-directories)

manuals
     for names of manual pages

mailboxes
     for e-mail folders

maps
     for map names (e.g. NIS maps)

messages
     used to look up the format style for messages

modifiers
     for names of X modifiers

modules
     for modules (e.g. zsh modules)

my-accounts
     used to look up the users-hosts style

named-directories
     for named directories (you wouldn't have guessed that, would you?)

names
     for all kinds of names

newsgroups
     for USENET groups

nicknames
     for nicknames of NIS maps

options
     for command options

original
     used by the _approximate, _correct and _expand completers when
     offering the original string as a match

other-accounts
     used to look up the users-hosts style

packages
     for packages (e.g. rpm or installed Debian packages)

parameters
     for names of parameters

path-directories
     for names of directories found by searching the cdpath array when
     completing arguments of cd and related builtin commands (compare
     local-directories)

paths
     used to look up the values of the expand, ambiguous and
     special-dirs styles

pods
     for perl pods (documentation files)

ports
     for communication ports

prefixes
     for prefixes (like those of a URL)

printers
     for print queue names

processes
     for process identifiers

processes-names
     used to look up the command style when generating the names of
     processes for killall

sequences
     for sequences (e.g. mh sequences)

sessions
     for sessions in the zftp function suite

signals
     for signal names

strings
     for strings (e.g. the replacement strings for the cd builtin
     command)

styles
     for styles used by the zstyle builtin command

suffixes
     for filename extensions

tags
     for tags (e.g. rpm tags)

targets
     for makefile targets

time-zones
     for time zones (e.g. when setting the TZ parameter)

types
     for types of whatever (e.g. address types for the xhost command)

urls
     used to look up the urls and local styles when completing URLs

users
     for usernames

values
     for one of a set of values in certain lists

variant
     used by _pick_variant to look up the command to run when
     determining what program is installed for a particular command
     name.

visuals
     for X visuals

warnings
     used to look up the format style for warnings

widgets
     for zsh widget names

windows
     for IDs of X windows

zsh-options
     for shell options

Standard Styles
---------------

Note that the values of several of these styles represent boolean
values.  Any of the strings `true', `on', `yes', and `1' can be used
for the value `true' and any of the strings `false', `off', `no', and
`0' for the value `false'.  The behavior for any other value is
undefined except where explicitly mentioned.  The default value may be
either true or false if the style is not set.

Some of these styles are tested first for every possible tag
corresponding to a type of match, and if no style was found, for the
default tag.  The most notable styles of this type are menu,
list-colors and styles controlling completion listing such as
list-packed and last-prompt).  When tested for the default tag, only
the FUNCTION field of the context will be set so that a style using the
default tag will normally be defined along the lines of:

     zstyle ':completion:*:default' menu ...

accept-exact
     This is tested for the default tag in addition to the tags valid
     for the current context.  If it is set to `true' and any of the
     trial matches is the same as the string on the command line, this
     match will immediately be accepted (even if it would otherwise be
     considered ambiguous).

     When completing pathnames (where the tag used is `paths') this
     style accepts any number of patterns as the value in addition to
     the boolean values.  Pathnames matching one of these patterns will
     be accepted immediately even if the command line contains some
     more partially typed pathname components and these match no file
     under the directory accepted.

     This style is also used by the _expand completer to decide if
     words beginning with a tilde or parameter expansion should be
     expanded.  For example, if there are parameters foo and foobar,
     the string `$foo' will only be expanded if accept-exact is set to
     `true'; otherwise the completion system will be allowed to
     complete $foo to $foobar.

add-space
     This style is used by the _expand completer.  If it is true (the
     default), a space will be inserted after all words resulting from
     the expansion, or a slash in the case of directory names.  If the
     value is `file', the completer will only add a space to names of
     existing files.  Either a boolean true or the value `file' may be
     combined with `subst', in which case the completer will not add a
     space to words generated from the expansion of a substitution of
     the form `$(...)' or `${...}'.

     The _prefix completer uses this style as a simple boolean value to
     decide if a space should be inserted before the suffix.

ambiguous
     This applies when completing non-final components of filename
     paths, in other words those with a trailing slash.  If it is set,
     the cursor is left after the first ambiguous component, even if
     menu completion is in use.  The style is always tested with the
     paths tag.

assign-list
     When completing after an equals sign that is being treated as an
     assignment, the completion system normally completes only one
     filename.  In some cases the value  may be a list of filenames
     separated by colons, as with PATH and similar parameters.  This
     style can be set to a list of patterns matching the names of such
     parameters.

     The default is to complete lists when the word on the line already
     contains a colon.

auto-description
     If set, this style's value will be used as the description for
     options that are not described by the completion functions, but
     that have exactly one argument.  The sequence `%d' in the value
     will be replaced by the description for this argument.  Depending
     on personal preferences, it may be useful to set this style to
     something like `specify: %d'.  Note that this may not work for
     some commands.

avoid-completer
     This is used by the _all_matches completer to decide if the string
     consisting of all matches should be added to the list currently
     being generated.  Its value is a list of names of completers.  If
     any of these is the name of the completer that generated the
     matches in this completion, the string will not be added.

     The default value for this style is `_expand _old_list _correct
     _approximate', i.e. it contains the completers for which a string
     with all matches will almost never be wanted.

cache-path
     This style defines the path where any cache files containing dumped
     completion data are stored.  It defaults to
     `$ZDOTDIR/.zcompcache', or `$HOME/.zcompcache' if $ZDOTDIR is not
     defined.  The completion cache will not be used unless the
     use-cache style is set.

cache-policy
     This style defines the function that will be used to determine
     whether a cache needs rebuilding.  See the section on the
     _cache_invalid function below.

call-command
     This style is used in the function for commands such as make and
     ant where calling the command directly to generate matches suffers
     problems such as being slow or, as in the case of make can
     potentially causes actions in the makefile to be executed. If it
     is set to `true' the command is called to generate matches. The
     default value of this style is `false'.

command
     In many places, completion functions need to call external
     commands to generate the list of completions.  This style can be
     used to override the command that is called in some such cases.
     The elements of the value are joined with spaces to form a command
     line to execute.  The value can also start with a hyphen, in which
     case the usual command will be added to the end; this is most
     useful for putting `builtin' or `command' in front to make sure
     the appropriate version of a command is called, for example to
     avoid calling a shell function with the same name as an external
     command.

     As an example, the completion function for process IDs uses this
     style with the processes tag to generate the IDs to complete and
     the list of processes to display (if the verbose style is `true').
     The list produced by the command should look like the output of the
     ps command.  The first line is not displayed, but is searched for
     the string `PID' (or `pid') to find the position of the process
     IDs in the following lines.  If the line does not contain `PID',
     the first numbers in each of the other lines are taken as the
     process IDs to complete.

     Note that the completion function generally has to call the
     specified command for each attempt to generate the completion
     list.  Hence care should be taken to specify only commands that
     take a short time to run, and in particular to avoid any that may
     never terminate.

commands
     This is used by the function completing sub-commands for the system
     initialisation scripts (residing in /etc/init.d or somewhere not
     too far away from that).  Its values give the default commands to
     complete for those commands for which the completion function isn't
     able to find them out automatically.  The default for this style
     are the two strings `start' and `stop'.

complete
     This is used by the _expand_alias function when invoked as a
     bindable command.  If it set to `true' and the word on the command
     line is not the name of an alias, matching alias names will be
     completed.

completer
     The strings given as the value of this style provide the names of
     the completer functions to use. The available completer functions
     are described in *Note Control Functions::.

     Each string may be either the name of a completer function or a
     string of the form `FUNCTION:NAME'.  In the first case the
     COMPLETER field of the context will contain the name of the
     completer without the leading underscore and with all other
     underscores replaced by hyphens.  In the second case the FUNCTION
     is the name of the completer to call, but the context will contain
     the user-defined NAME in the COMPLETER field of the context.  If
     the NAME starts with a hyphen, the string for the context will be
     build from the name of the completer function as in the first case
     with the NAME appended to it.  For example:

          zstyle ':completion:*' completer _complete _complete:-foo

     Here, completion will call the _complete completer twice, once
     using `complete' and once using `complete-foo' in the COMPLETER
     field of the context.  Normally, using the same completer more
     than once only makes sense when used with the `FUNCTIONS:NAME'
     form, because otherwise the context name will be the same in all
     calls to the completer; possible exceptions to this rule are the
     _ignored and _prefix completers.

     The default value for this style is `_complete _ignored': only
     completion will be done, first using the ignored-patterns style
     and the $fignore array and then without ignoring matches.

condition
     This style is used by the _list completer function to decide if
     insertion of matches should be delayed unconditionally. The
     default is `true'.

disabled
     If this is set to `true', the _expand_alias completer and bindable
     command will try to expand disabled aliases, too.  The default is
     `false'.

disable-stat
     This is used with an empty tag by the _cvs function to decide
     whether the zsh/stat module should be used to generate names of
     modified files in the appropriate places (this is its only use).
     If the style is set, completion will use the ls command.

domains
     A list of names of network domains for completion.  If this is not
     set, domain names will be taken from the file /etc/resolv.conf.

expand
     This style is used when completing strings consisting of multiple
     parts, such as path names.

     If one of its values is the string `prefix', the partially typed
     word from the line will be expanded as far as possible even if
     trailing parts cannot be completed.

     If one of its values is the string `suffix', matching names for
     components after the first ambiguous one will also be added.  This
     means that the resulting string is the longest unambiguous string
     possible.  However, menu completion can be used to cycle through
     all matches.

fake
     This style may be set for any completion context.  It specifies
     additional strings that will always be completed in that context.
     The form of each string is `VALUE:DESCRIPTION'; the colon and
     description may be omitted, but any literal colons in VALUE must
     be quoted with a backslash.  Any DESCRIPTION provided is shown
     alongside the value in completion listings.

     It is important to use a sufficiently restrictive context when
     specifying fake strings.  Note that the styles fake-files and
     fake-parameters provide additional features when completing files
     or parameters.

fake-files
     This style is used when completing files and looked up without a
     tag.  Its values are of the form `DIR:NAMES...'.  This will add
     the NAMES (strings separated by spaces) as possible matches when
     completing in the directory DIR, even if no such files really
     exist.

     This can be useful on systems that support special filesystems
     whose top-level pathnames can not be listed or generated with glob
     patterns.  It can also be used for directories for which one does
     not have read permission.

fake-parameters
     This is used by the completion function for parameter names.  Its
     values are names of parameters that might not yet be set but
     should be completed nonetheless.  Each name may also be followed
     by a colon and a string specifying the type of the parameter (like
     `scalar', `array' or `integer').  If the type is given, the name
     will only be completed if parameters of that type are required in
     the particular context.  Names for which no type is specified will
     always be completed.

file-patterns
     This is used by the standard function for completing filenames,
     _files.  If the style is unset up to three tags are offered,
     `globbed-files',`directories' and `all-files', depending on the
     types of files  expected by the caller of _files.  The first two
     (`globbed-files' and `directories') are normally offered together
     to make it easier to complete files in sub-directories.

     The file-patterns style provides alternatives to the default tags,
     which are not used.  Its value consists of elements of the form
     `PATTERN:TAG'; each string may contain any number of such
     specifications separated by spaces.

     The PATTERN is a pattern that is to be used to generate filenames.
     Any occurrence of the sequence `%p' is replaced by any pattern(s)
     passed by the function calling _files.  Colons in the pattern must
     be preceded by a backslash to make them distinguishable from the
     colon before the TAG.  If more than one pattern is needed, the
     patterns can be given inside braces, separated by commas.

     The TAGs of all strings in the value will be offered by _files and
     used when looking up other styles.  Any TAGs in the same word will
     be offered at the same time and before later words.  If no `:TAG'
     is given the `files' tag will be used.

     The TAG may also be followed by an optional second colon and a
     description, which will be used for the `%d' in the value of the
     format style (if that is set) instead of the default description
     supplied by the completion function.  If the description given
     here contains itself a `%d', that is replaced with the description
     supplied by the completion function.

     For example, to make the rm command first complete only names of
     object files and then the names of all files if there is no
     matching object file:

          zstyle ':completion:*:*:rm:*' file-patterns \
              '*.o:object-files' '%p:all-files'

     To alter the default behaviour of file completion -- offer files
     matching a pattern and directories on the first attempt, then all
     files -- to offer only matching files on the first attempt, then
     directories, and finally all files:

          zstyle ':completion:*' file-patterns \
              '%p:globbed-files' '*(-/):directories' '*:all-files'

     This works even where there is no special pattern: _files matches
     all files using the pattern `*' at the first step and stops when it
     sees this pattern.  Note also it will never try a pattern more
     than once for a single completion attempt.

     During the execution of completion functions, the EXTENDED_GLOB
     option is in effect, so the characters `#', `~' and `^' have
     special meanings in the patterns.

file-sort
     The standard filename completion function uses this style without
     a tag to determine in which order the names should be listed; menu
     completion will cycle through them in the same order.  The possible
     values are: `size' to sort by the size of the file; `links' to
     sort by the number of links to the file; `modification' (or `time'
     or `date') to sort by the last modification time; `access' to sort
     by the last access time; and `inode' (or `change') to sort by the
     last inode change time.  If the style is set to any other value,
     or is unset, files will be sorted alphabetically by name.  If the
     value contains the string `reverse', sorting is done in the
     opposite order.

filter
     This is used by the LDAP plugin for e-mail address completion to
     specify the attributes to match against when filtering entries.
     So for example, if the style is set to `sn', matching is done
     against surnames.  Standard LDAP filtering is used so normal
     completion matching is bypassed.  If this style is not set, the
     LDAP plugin is skipped.  You may also need to set the command
     style to specify how to connect to your LDAP server.

force-list
     This forces a list of completions to be shown at any point where
     listing is done, even in cases where the list would usually be
     suppressed.  For example, normally the list is only shown if there
     are at least two different matches.  By setting this style to
     `always', the list will always be shown, even if there is only a
     single match that will immediately be accepted.  The style may also
     be set to a number.  In this case the list will be shown if there
     are at least that many matches, even if they would all insert the
     same string.

     This style is tested for the default tag as well as for each tag
     valid for the current completion.  Hence the listing can be forced
     only for certain types of match.

format
     If this is set for the descriptions tag, its value is used as a
     string to display above matches in completion lists.  The sequence
     `%d' in this string will be replaced with a short description of
     what these matches are.  This string may also contain the
     sequences to specify output attributes, such as `%B', `%S' and
     `%{...%}'.

     The style is tested with each tag valid for the current completion
     before it is tested for the descriptions tag.  Hence different
     format strings can be defined for different types of match.

     Note also that some completer functions define additional
     `%'-sequences.  These are described for the completer functions
     that make use of them.

     Some completion functions display messages that may be customised
     by setting this style for the messages tag.  Here, the `%d' is
     replaced with a message given by the completion function.

     Finally, the format string is looked up with the warnings tag, for
     use when no matches could be generated at all.  In this case the
     `%d' is replaced with the descriptions for the matches that were
     expected separated by spaces.  The sequence `%D' is replaced with
     the same descriptions separated by newlines.

     It is possible to use printf-style field width specifiers with `%d'
     and similar escape sequences.  This is handled by the zformat
     builtin command from the zsh/zutil module, see *Note The zsh/zutil
     Module::.

glob
     This is used by the _expand completer.  If it is set to `true'
     (the default), globbing will be attempted on the words resulting
     from a previous substitution (see the substitute style) or else
     the original string from the line.

global
     If this is set to `true' (the default), the _expand_alias
     completer and bindable command will try to expand global aliases.

group-name
     The completion system can group different types of matches, which
     appear in separate lists.  This style can be used to give the
     names of groups for particular tags.  For example, in command
     position the completion system generates names of builtin and
     external commands, names of aliases, shell functions and
     parameters and reserved words as possible completions.  To have
     the external commands and shell functions listed separately:

          zstyle ':completion:*:*:-command-:*:commands' group-name commands
          zstyle ':completion:*:*:-command-:*:functions' group-name functions

     As a consequence, any match with the same tag will be displayed in
     the same group.

     If the name given is the empty string the name of the tag for the
     matches will be used as the name of the group.  So, to have all
     different types of matches displayed separately, one can just set:

          zstyle ':completion:*' group-name ''

     All matches for which no group name is defined will be put in a
     group named -default-.

group-order
     This style is additional to the group-name style to specify the
     order for display of the groups defined by that style (compare
     tag-order, which determines which completions appear at all).  The
     groups named are shown in the given order; any other groups are
     shown in the order defined by the completion function.

     For example, to have names of builtin commands, shell functions and
     external commands appear in that order when completing in command
     position:

          zstyle ':completion:*:*:-command-:*' group-order \
                 builtins functions commands

groups
     A list of names of UNIX groups.  If this is not set, group names
     are taken from the YP database or the file `/etc/group'.

hidden
     If this is set to true, matches for the given context will not be
     listed, although any description for the matches set with the
     format style will be shown.  If it is set to `all', not even the
     description will be displayed.

     Note that the matches will still be completed; they are just not
     shown in the list.  To avoid having matches considered as possible
     completions at all, the tag-order style can be modified as
     described below.

hosts
     A list of names of hosts that should be completed.  If this is not
     set, hostnames are taken from the file `/etc/hosts'.

hosts-ports
     This style is used by commands that need or accept hostnames and
     network ports.  The strings in the value should be of the form
     `HOST:PORT'.  Valid ports are determined by the presence of
     hostnames; multiple ports for the same host may appear.

ignore-line
     This is tested for each tag valid for the current completion.  If
     it is set to `true', none of the words that are already on the line
     will be considered as possible completions.  If it is set to
     `current', the word the cursor is on will not be considered as a
     possible completion.  The value `current-shown' is similar but only
     applies if the list of completions is currently shown on the
     screen.  Finally, if the style is set to `other', no word apart
     from the current one will be considered as a possible completion.

     The values `current' and `current-shown' are a bit like the
     opposite of the accept-exact style:  only strings with missing
     characters will be completed.

     Note that you almost certainly don't want to set this to `true' or
     `other' for a general context such as `:completion:*'.  This is
     because it would disallow completion of, for example, options
     multiple times even if the command in question accepts the option
     more than once.

ignore-parents
     The style is tested without a tag by the function completing
     pathnames in order to determine whether to ignore the names of
     directories already mentioned in the current word, or the name of
     the current working directory.  The value must include one or both
     of the following strings:

    parent
          The name of any directory whose path is already contained in
          the word on the line is ignored.  For example, when
          completing after foo/../, the directory foo will not be
          considered a valid completion.

    pwd
          The name of the current working directory will not be
          completed; hence, for example, completion after ../ will not
          use the name of the current directory.

     In addition, the value may include one or both of:

    ..
          Ignore the specified directories only when the word on the
          line contains the substring `../'.

    directory
          Ignore the specified directories only when names of
          directories are completed, not when completing names of files.

     Excluded values act in a similar fashion to values of the
     ignored-patterns style, so they can be restored to consideration by
     the _ignored completer.

ignored-patterns
     A list of patterns; any trial completion matching one of the
     patterns will be excluded from consideration.  The _ignored
     completer can appear in the list of completers to restore the
     ignored matches.  This is a more configurable version of the shell
     parameter $fignore.

     Note that the EXTENDED_GLOB option is set during the execution of
     completion functions, so the characters `#', `~' and `^' have
     special meanings in the patterns.

insert
     This style is used by the _all_matches completer to decide whether
     to insert the list of all matches unconditionally instead of
     adding the list as another match.

insert-ids
     When completing process IDs, for example as arguments to the kill
     and wait builtins the name of a command may be converted to the
     appropriate process ID.  A problem arises when the process name
     typed is not unique.  By default (or if this style is set
     explicitly to `menu') the name will be converted immediately to a
     set of possible IDs, and menu completion will be started to cycle
     through them.

     If the value of the style is `single', the shell will wait until
     the user has typed enough to make the command unique before
     converting the name to an ID; attempts at completion will be
     unsuccessful until that point.  If the value is any other string,
     menu completion will be started when the string typed by the user
     is longer than the common prefix to the corresponding IDs.

insert-tab
     If this is set to `true', the completion system will insert a TAB
     character (assuming that was used to start completion) instead of
     performing completion when there is no non-blank character to the
     left of the cursor.  If it is set to `false', completion will be
     done even there.

     The value may also contain the substrings `pending' or
     `pending=VAL'.  In this case, the typed character will be inserted
     instead of staring completion when there is unprocessed input
     pending.  If a VAL is given, completion will not be done if there
     are at least that many characters of unprocessed input.  This is
     often useful when pasting characters into a terminal.  Note
     however, that it relies on the $PENDING special parameter from the
     zsh/zle module being set properly which is not guaranteed on all
     platforms.

     The default value of this style is `true' except for completion
     within vared builtin command where it is `false'.

insert-unambiguous
     This is used by the _match and _approximate completers.  These
     completers are often used with menu completion since the word typed
     may bear little resemblance to the final completion.  However, if
     this style is `true', the completer will start menu completion
     only if it could find no unambiguous initial string at least as
     long as the original string typed by the user.

     In the case of the _approximate completer, the completer field in
     the context will already have been set to one of correct-NUM or
     approximate-NUM, where NUM is the number of errors that were
     accepted.

     In the case of the _match completer, the style may also be set to
     the string `pattern'.  Then the pattern on the line is left
     unchanged if it does not match unambiguously.

keep-prefix
     This style is used by the _expand completer.  If it is `true', the
     completer will try to keep a prefix containing a tilde or parameter
     expansion.  Hence, for example, the string `~/f*' would be
     expanded to `~/foo' instead of `/home/user/foo'.  If the style is
     set to `changed' (the default), the prefix will only be left
     unchanged if there were other changes between the expanded words
     and the original word from the command line.  Any other value
     forces the prefix to be expanded unconditionally.

     The behaviour of expand when this style is true is to cause _expand
     to give up when a single expansion with the restored prefix is the
     same as the original; hence any remaining completers may be called.

last-prompt
     This is a more flexible form of the ALWAYS_LAST_PROMPT option.  If
     it is true, the completion system will try to return the cursor to
     the previous command line after displaying a completion list.  It
     is tested for all tags valid for the current completion, then the
     default tag.  The cursor will be moved back to the previous line
     if this style is `true' for all types of match.  Note that unlike
     the ALWAYS_LAST_PROMPT option this is independent of the numeric
     prefix argument.

list
     This style is used by the _history_complete_word bindable command.
     If it is set to `true' it has no effect.  If it is set to `false'
     matches will not be listed.  This overrides the setting of the
     options controlling listing behaviour, in particular AUTO_LIST.
     The context always starts with `:completion:history-words'.

list-colors
     If the zsh/complist module is loaded, this style can be used to set
     color specifications.  This mechanism replaces the use of the
     ZLS_COLORS and ZLS_COLOURS parameters described in *Note The
     zsh/complist Module::, but the syntax is the same.

     If this style is set for the default tag, the strings in the value
     are taken as specifications that are to be used everywhere.  If it
     is set for other tags, the specifications are used only for
     matches of the type described by the tag.  For this to work best,
     the group-name style must be set to an empty string.

     In addition to setting styles for specific tags, it is also
     possible to use group names specified explicitly by the group-name
     tag together with the `(group)' syntax allowed by the ZLS_COLORS
     and ZLS_COLOURS parameters and simply using the default tag.

     It is possible to use any color specifications already set up for
     the GNU version of the ls command:

          zstyle ':completion:*:default' list-colors ${(s.:.)LS_COLORS}

     The default colors are the same as for the GNU ls command and can
     be obtained by setting the style to an empty string (i.e. '').

list-grouped
     If this style is `true' (the default), the completion system will
     try to make certain completion listings more compact by grouping
     matches.  For example, options for commands that have the same
     description (shown when the verbose style is set to `true') will
     appear as a single entry.  However, menu selection can be used to
     cycle through all the matches.

list-packed
     This is tested for each tag valid in the current context as well
     as the default tag.  If it is set to `true', the corresponding
     matches appear in listings as if the LIST_PACKED option were set.
     If it is set to `false', they are listed normally.

list-prompt
     If this style is set for the default tag, completion lists that
     don't fit on the screen can be scrolled (see *Note The
     zsh/complist Module::).  The value, if not the empty string, will
     be displayed after every screenful and the shell will prompt for a
     key press; if the style is set to the empty string, a default
     prompt will be used.

     The value may contain the escape sequences: `%l' or `%L', which
     will be replaced by the number of the last line displayed and the
     total number of lines; `%m' or `%M', the number of the  last match
     shown and the total number of matches; and `%p' and `%P', `Top'
     when at the beginning of the list, `Bottom' when at the end and the
     position shown as a percentage of the total length otherwise.  In
     each case the form with the uppercase letter will be replaced by a
     string of fixed width, padded to the  right with spaces, while the
     lowercase form will be replaced by a variable width string.  As in
     other prompt strings, the escape sequences `%S', `%s', `%B', `%b',
     `%U', `%u' for entering and leaving the display modes standout,
     bold and underline are also available, as is the form `%{...%}'
     for enclosing escape sequences which display with zero width.

list-rows-first
     This style is tested in the same way as the list-packed style and
     determines whether matches are to be listed in a rows-first
     fashion as if the LIST_ROWS_FIRST option were set.

list-suffixes
     This style is used by the function that completes filenames.  If
     it is true, and completion is attempted on a string containing
     multiple partially typed pathname components, all ambiguous
     components will be shown.  Otherwise, completion stops at the
     first ambiguous component.

list-separator
     The value of this style is used in completion listing to separate
     the string to complete from a description when possible (e.g. when
     completing options).  It defaults to `--' (two hyphens).

local
     This is for use with functions that complete URLs for which the
     corresponding files are available directly from the filing system.
     Its value should consist of three strings: a hostname, the path to
     the default web pages for the server, and the directory name used
     by a user placing web pages within their home area.

     For example:

          zstyle ':completion:*' local toast \
              /var/http/public/toast public_html

     Completion after `http://toast/stuff/' will look for files in the
     directory /var/http/public/toast/stuff,  while completion after
     `http://toast/~yousir/' will look for files in the directory
     ~yousir/public_html.

mail-directory
     If set, zsh will assume that mailbox files can be found in the
     directory specified.  It defaults to `~/Mail'.

match-original
     This is used by the _match completer.  If it is set to only,
     _match will try to generate matches without inserting a `*' at the
     cursor position.  If set to any other non-empty value, it will
     first try to generate matches without inserting the `*' and if
     that yields no matches, it will try again with the `*' inserted.
     If it is unset or set to the empty string, matching will only be
     performed with the `*' inserted.

matcher
     This style is tested separately for each tag valid in the current
     context.  Its value is added to any match specifications given by
     the matcher-list style.  It should be in the form described in
     *Note Matching Control::.

matcher-list
     This style can be set to a list of match specifications that are to
     be applied everywhere. Match specifications are described in *Note
     Matching Control::.  The completion system will try them one after
     another for each completer selected.  For example, to try first
     simple completion and, if that generates no matches,
     case-insensitive completion:

          zstyle ':completion:*' matcher-list '' 'm:{a-zA-Z}={A-Za-z}'

     By default each specification replaces the previous one; however,
     if a specification is prefixed with +, it is added to the existing
     list.  Hence it is possible to create increasingly general
     specifications without repetition:

          zstyle ':completion:*' matcher-list '' '+m{a-Z}={A-Z}' '+m{A-Z}={a-z}'

     It is possible to create match specifications valid for particular
     completers by using the third field of the context.  For example,
     to use the completers _complete and _prefix but only allow
     case-insensitive completion with _complete:

          zstyle ':completion:*' completer _complete _prefix
          zstyle ':completion:*:complete:*' matcher-list \
                 '' 'm:{a-zA-Z}={A-Za-z}'

     User-defined names, as explained for the completer style, are
     available.  This makes it possible to try the same completer more
     than once with different match specifications each time.  For
     example, to try normal completion without a match specification,
     then normal completion with case-insensitive matching, then
     correction, and finally partial-word completion:

          zstyle ':completion:*' completer _complete _correct _complete:foo
          zstyle ':completion:*:complete:*' matcher-list \
              '' 'm:{a-zA-Z}={A-Za-z}'
          zstyle ':completion:*:foo:*' matcher-list \
              'm:{a-zA-Z}={A-Za-z} r:|[-_./]=* r:|=*'

     If the style is unset in any context no match specification is
     applied.  Note also that some completers such as _correct and
     _approximate do not use the match specifications at all, though
     these completers will only ever called once even if the
     matcher-list contains more than one element.

     Where multiple specifications are useful, note that the _entire_
     completion is done for each element of matcher-list, which can
     quickly reduce the shell's performance.  As a rough rule of thumb,
     one to three strings will give acceptable performance.  On the
     other hand, putting multiple space-separated values into the same
     string does not have an appreciable impact on performance.

max-errors
     This is used by the _approximate and _correct completer functions
     to determine the maximum number of errors to allow.  The completer
     will try to generate completions by first allowing one error, then
     two errors, and so on, until either a match or matches were found
     or the maximum number of errors given by this style has been
     reached.

     If the value for this style contains the string `numeric', the
     completer function will take any numeric argument as the maximum
     number of errors allowed. For example, with

          zstyle ':completion:*:approximate:::' max-errors 2 numeric

     two errors are allowed if no numeric argument is given, but with a
     numeric argument of six (as in `ESC-6 TAB'), up to six errors are
     accepted.  Hence with a value of `0 numeric', no correcting
     completion will be attempted unless a numeric argument is given.

     If the value contains the string `not-numeric', the completer will
     _not_ try to generate corrected completions when given a numeric
     argument, so in this case the number given should be greater than
     zero.  For example, `2 not-numeric' specifies that correcting
     completion with two errors will usually be performed, but if a
     numeric argument is given, correcting completion will not be
     performed.

     The default value for this style is `2 numeric'.

max-matches-width
     This style is used to determine the trade off between the width of
     the display used for matches and the width used for their
     descriptions when the verbose style is in effect.  The value gives
     the number of display columns to reserve for the matches.  The
     default is half the width of the screen.

     This has the most impact when several matches have the same
     description and so will be grouped together.  Increasing the style
     will allow more matches to be grouped together; decreasing it will
     allow more of the description to be visible.

menu
     If this is true in the context of any of the tags defined for the
     current completion menu completion will be used.  The value for a
     specific tag will take precedence over that for the `default' tag.

     If none of the values found in this way is true but at least one
     is set to `auto', the shell behaves as if the AUTO_MENU option is
     set.

     If one of the values is explicitly set to false, menu completion
     will be explicitly turned off, overriding the MENU_COMPLETE option
     and other settings.

     In the form `yes=NUM', where `yes' may be any of the true values
     (`yes', `true', `on' and `1'), menu completion will be turned on
     if there are at least NUM matches.  In the form `yes=long', menu
     completion will be turned on if the list does not fit on the
     screen.  This does not activate menu completion if the widget
     normally only lists completions, but menu completion can be
     activated in that case with the value `yes=long-list' (Typically,
     the value `select=long-list' described later is more useful as it
     provides control over scrolling.)

     Similarly, with any of the `false' values (as in `no=10'), menu
     completion will _not_ be used if there are NUM or more matches.

     The value of this widget also controls menu selection, as
     implemented by the zsh/complist module.  The following values may
     appear either alongside or instead of the values above.

     If the value contains the string `select', menu selection will be
     started unconditionally.

     In the form `select=NUM', menu selection will only be started if
     there are at least NUM matches.  If the values for more than one
     tag provide a number, the smallest number is taken.

     Menu selection can be turned off explicitly by defining a value
     containing the string`no-select'.

     It is also possible to start menu selection only if the list of
     matches does not fit on the screen by using the value
     `select=long'.  To start menu selection even if the current widget
     only performs listing, use the value `select=long-list'.

     To turn on menu completion or menu selection when a there are a
     certain number of matches _or_ the list of matches does not fit on
     the screen, both of `yes=' and `select=' may be given twice, once
     with a number and once with `long' or `long-list'.

     Finally, it is possible to activate two special modes of menu
     selection.  The word `interactive' in the value causes interactive
     mode to be entered immediately when menu selection is started; see
     *Note The zsh/complist Module:: for a description of interactive
     mode.  Including the string `search' does the same for incremental
     search mode.  To select backward incremental search, include the
     string `search-backward'.  )

muttrc
     If set, gives the location of the mutt configuration file.  It
     defaults to `~/.muttrc'.

numbers
     This is used with the jobs tag.  If it is `true', the shell will
     complete job numbers instead of the shortest unambiguous prefix of
     the job command text.  If the value is a number, job numbers will
     only be used if that many words from the job descriptions are
     required to resolve ambiguities.  For example, if the value is
     `1', strings will only be used if all jobs differ in the first
     word on their command lines.

old-list
     This is used by the _oldlist completer.  If it is set to `always',
     then standard widgets which perform listing will retain the
     current list of matches, however they were generated; this can be
     turned off explicitly with the value `never', giving the behaviour
     without the _oldlist completer.  If the style is unset, or any
     other value, then the existing list of completions is displayed if
     it is not already; otherwise, the standard completion list is
     generated; this is the default behaviour of _oldlist.  However, if
     there is an old list and this style contains the name of the
     completer function that generated the list, then the old list will
     be used even if it was generated by a widget which does not do
     listing.

     For example, suppose you type ^Xc to use the _correct_word widget,
     which generates a list of corrections for the word under the
     cursor.  Usually, typing ^D would generate a standard list of
     completions for the word on the command line, and show that.  With
     _oldlist, it will instead show the list of corrections already
     generated.

     As another example consider the _match completer: with the
     insert-unambiguous style set to `true' it inserts only a common
     prefix string, if there is any.  However, this may remove parts of
     the original pattern, so that further completion could produce
     more matches than on the first attempt.  By using the _oldlist
     completer and setting this style to _match, the list of matches
     generated on the first attempt will be used again.

old-matches
     This is used by the _all_matches completer to decide if an old
     list of matches should be used if one exists.  This is selected by
     one of the `true' values or by the string `only'.  If the value is
     `only', _all_matches will only use an old list and won't have any
     effect on the list of matches currently being generated.

     If this style is set it is generally unwise to call the
     _all_matches completer unconditionally.  One possible use is for
     either this style or the completer style to be defined with the -e
     option to zstyle to make the style conditional.

old-menu
     This is used by the _oldlist completer.  It controls how menu
     completion behaves when a completion has already been inserted and
     the user types a standard completion key such as TAB.  The default
     behaviour of _oldlist is that menu completion always continues
     with the existing list of completions.  If this style is set to
     `false', however, a new completion is started if the old list was
     generated by a different completion command; this is the behaviour
     without the _oldlist completer.

     For example, suppose you type ^Xc to generate a list of
     corrections, and menu completion is started in one of the usual
     ways.  Usually, or with this style set to false, typing TAB at
     this point would start trying to complete the line as it now
     appears.  With _oldlist, it instead continues to cycle through the
     list of corrections.

original
     This is used by the _approximate and _correct completers to decide
     if the original string should be added as a possible completion.
     Normally, this is done only if there are at least two possible
     corrections, but if this style is set to `true', it is always
     added.  Note that the style will be examined with the completer
     field in the context name set to correct-NUM or approximate-NUM,
     where NUM is the number of errors that were accepted.

packageset
     This style is used when completing arguments of the Debian `dpkg'
     program.  It contains an override for the default package set for
     a given context.  For example,

          zstyle ':completion:*:complete:dpkg:option--status-1:*' \
                         packageset avail

     causes available packages, rather than only installed packages, to
     be completed for `dpkg -status'.

path
     The function that completes color names uses this style with the
     colors tag.  The value should be the pathname of a file containing
     color names in the format of an X11 rgb.txt file.  If the style is
     not set but this file is found in one of various standard
     locations it will be used as the default.

pine-directory
     If set, specifies the directory containing PINE mailbox files.  It
     defaults to `~/mail'.

ports
     A list of Internet service names (network ports) to complete.  If
     this is not set, service names are taken from the file
     `/etc/services'.

prefix-hidden
     This is used for certain completions which share a common prefix,
     for example command options beginning with dashes.  If it is
     `true', the prefix will not be shown in the list of matches.

     The default value for this style is `false'.

prefix-needed
     This, too, is used for matches with a common prefix.  If it is set
     to `true' this common prefix must be typed by the user to generate
     the matches.  In the case of command options, this means that the
     initial `-', `+', or `--' must be typed explicitly before option
     names will be completed.

     The default value for this style is `true'.

preserve-prefix
     This style is used when completing path names.  Its value should
     be a pattern matching an initial prefix of the word to complete
     that should be left unchanged under all circumstances.  For
     example, on some Unices an initial `//' (double slash) has a
     special meaning; setting this style to the string `//' will
     preserve it.  As another example, setting this style to `?:/'
     under Cygwin would allow completion after `a:/...' and so on.

range
     This is used by the _history completer and the
     _history_complete_word bindable command to decide which words
     should be completed.

     If it is a singe number, only the last N words from the history
     will be completed.

     If it is a range of the form `MAX:SLICE', the last SLICE words
     will be completed; then if that yields no matches, the SLICE words
     before those will be tried and so on.  This process stops either
     when at least one match was been found, or MAX words have been
     tried.

     The default is to complete all words from the history at once.

regular
     This style is used by the _expand_alias completer and bindable
     command.  If set to `true' (the default), regular aliases will be
     expanded but only in command position.  If it is set to `false',
     regular aliases will never be expanded.   If it is set to `always',
     regular aliases will be expanded even if not in command position.

remote-access
     If set to false, certain commands will be prevented from making
     Internet connections to retrieve remote information.  This
     includes the completion for the CVS command.

     It is not always possible to know if connections are in fact to a
     remote site, so some may be prevented unnecessarily.

remove-all-dups
     The _history_complete_word bindable command and the _history
     completer use this to decide if all duplicate matches should be
     removed, rather than just consecutive duplicates.

select-prompt
     If this is set for the default tag, its value will be displayed
     during menu selection (see the menu style above) when the
     completion list does not fit on the screen as a whole.  The same
     escapes as for the list-prompt style are understood, except that
     the numbers refer to the match or line the mark is on.  A default
     prompt is used when the value is the empty string.

select-scroll
     This style is tested for the default tag and determines how a
     completion list is scrolled during a menu selection (see the menu
     style above) when the completion list does not fit on the screen
     as a whole.  If the value is `0' (zero), the list is scrolled by
     half-screenfuls; if it is a positive integer, the list is scrolled
     by the given number of lines; if it is a negative number, the list
     is scrolled by a screenful minus the absolute value of the given
     number of lines.  The default is to scroll by single lines.

separate-sections
     This style is used with the manuals tag when completing names of
     manual pages.  If it is `true', entries for different sections are
     added separately using tag names of the form `manual.X', where X
     is the section number.  When the group-name style is also in
     effect, pages from different sections will appear separately.
     This style is also used similarly with the words style when
     completing words for the dict command. It allows words from
     different dictionary databases to be added separately.  The
     default for this style is `false'.

single-ignored
     This is used by the _ignored completer when there is only one
     match.  If its value is `show', the single match will be displayed
     but not inserted.  If the value is `menu', then the single match
     and the original string are both added as matches and menu
     completion is started, making it easy to select either of them.

sort
     If set to `true', completing words from the command history sorts
     the words alphabetically instead of keeping them in the order in
     which they appear in the history (from youngest to oldest).

     This is also used by the _expand completer. If it is set to
     `true', the expansions generated will always be sorted.  If it is
     set to `menu', then the expansions are only sorted when they are
     offered as single strings but not in the string containing all
     possible expansions.

special-dirs
     Normally, the completion code will not produce the directory names
     `.' and `..' as possible completions.  If this style is set to
     `true', it will add both `.' and `..' as possible completions; if
     it is set to `..', only `..' will be added.

     The following example sets special-dirs to `..' when the current
     prefix is empty, is a single `.', or consists only of a path
     beginning with `../'.  Otherwise the value is `false'.

          zstyle -e ':completion:*' special-dirs \
             '[[ $PREFIX = (../)#(|.|..) ]] && reply=(..)'

squeeze-slashes
     If set to `true', sequences of slashes in filename paths (for
     example in `foo//bar') will be treated as a single slash.  This is
     the usual behaviour of UNIX paths.  However, by default the file
     completion function behaves as if there were a `*' between the
     slashes.

stop
     If set to `true', the _history_complete_word bindable command will
     stop once when reaching the beginning or end of the history.
     Invoking _history_complete_word will then wrap around to the
     opposite end of the history.  If this style is set to `false' (the
     default), _history_complete_word will loop immediately as in a
     menu completion.

strip-comments
     If set to `true', this style causes non-essential comment text to
     be removed from completion matches.  Currently it is only used when
     completing e-mail addresses where it removes any display name from
     the addresses, cutting them down to plain USER@HOST form.

subst-globs-only
     This is used by the _expand completer.  If it is set to `true',
     the expansion will only be used if it resulted from globbing;
     hence, if expansions resulted from the use of the substitute style
     described below, but these were not further changed by globbing,
     the expansions will be rejected.

     The default for this style is `false'.

substitute
     This boolean style controls whether the _expand completer will
     first try to expand all substitutions in the string (such as
     `$(...)' and `${...}').

     The default is `true'.

suffix
     This is used by the _expand completer if the word starts with a
     tilde or contains a parameter expansion.  If it is set to `true',
     the word will only be expanded if it doesn't have a suffix, i.e.
     if it is something like `~foo' or `$foo' rather than `~foo/' or
     `$foo/bar', unless that suffix itself contains characters eligible
     for expansion.  The default for this style is `true'.

tag-order
     This provides a mechanism for sorting how the tags available in a
     particular context will be used.

     The values for the style are sets of space-separated lists of tags.
     The tags in each value will be tried at the same time; if no match
     is found, the next value is used.  (See the file-patterns style for
     an exception to this behavior.)

     For example:

          zstyle ':completion:*:complete:-command-:*' tag-order \
              'commands functions'

     specifies that completion in command position first offers
     external commands and shell functions.  Remaining tags will be
     tried if no completions are found.

     In addition to tag names, each string in the value may take one of
     the following forms:

    -
          If any value consists of only a hyphen, then _only_ the tags
          specified in the other values are generated.  Normally all
          tags not explicitly selected are tried last if the specified
          tags fail to generate any matches.  This means that a single
          value consisting only of a single hyphen turns off completion.

    ! TAGS...
          A string starting with an exclamation mark specifies names of
          tags that are _not_ to be used.  The effect is the same as if
          all other possible tags for the context had been listed.

    TAG:LABEL ...
          Here, TAG is one of the standard tags and LABEL is an
          arbitrary name.  Matches are generated as normal but the name
          LABEL is used in contexts instead of TAG.  This is not useful
          in words starting with !.

          If the LABEL starts with a hyphen, the TAG is prepended to the
          LABEL to form the name used for lookup.  This can be used to
          make the completion system try a certain tag more than once,
          supplying different style settings for each attempt; see
          below for an example.

    TAG:LABEL:DESCRIPTION
          As before, but description will replace the `%d' in the value
          of the format style instead of the default description
          supplied by the completion function.  Spaces in the
          description must be quoted with a backslash.  A `%d' appearing
          in DESCRIPTION is replaced with the description given by the
          completion function.

     In any of the forms above the tag may be a pattern or several
     patterns in the form `{PAT1,PAT2...}'.  In this case all matching
     tags will be used except for any given explicitly in the same
     string.

     One use of these features is to try one tag more than once,
     setting other styles differently on each attempt, but still to use
     all the other tags without having to repeat them all.  For
     example, to make completion of function names in command position
     ignore all the completion functions starting with an underscore
     the first time completion is tried:

          zstyle ':completion:*:*:-command-:*' tag-order \
              'functions:-non-comp *' functions
          zstyle ':completion:*:functions-non-comp' ignored-patterns '_*'

     On the first attempt, all tags will be offered but the functions
     tag will be replaced by functions-non-comp.  The ignored-patterns
     style is set for this tag to exclude functions starting with an
     underscore.  If there are no matches, the second value of the
     tag-order style is used which completes functions using the default
     tag, this time presumably including all function names.

     The matches for one tag can be split into different groups.  For
     example:

          zstyle ':completion:*' tag-order \
              'options:-long:long\ options
               options:-short:short\ options
               options:-single-letter:single\ letter\ options'
          
          
          zstyle ':completion:*:options-long' ignored-patterns '[-+](|-|[^-]*)'
          zstyle ':completion:*:options-short' ignored-patterns '--*' '[-+]?'
          zstyle ':completion:*:options-single-letter' ignored-patterns '???*'

     With the group-names style set, options beginning with `--',
     options beginning with a single `-' or `+' but containing multiple
     characters, and single-letter options will be displayed in
     separate groups with different descriptions.

     Another use of patterns is to try multiple match specifications
     one after another.  The matcher-list style offers something
     similar, but it is tested very early in the completion system and
     hence can't be set for single commands nor for more specific
     contexts.  Here is how to try normal completion without any match
     specification and, if that generates no matches, try again with
     case-insensitive matching, restricting the effect to arguments of
     the command foo:

          zstyle ':completion:*:*:foo:*' tag-order '*' '*:-case'
          zstyle ':completion:*-case' matcher 'm:{a-z}={A-Z}'

     First, all the tags offered when completing after foo are tried
     using the normal tag name.  If that generates no matches, the
     second value of tag-order is used, which tries all tags again
     except that this time each has -case appended to its name for
     lookup of styles.  Hence this time the value for the matcher style
     from the second call to zstyle in the example is used to make
     completion case-insensitive.

     It is possible to use the -e option of the zstyle builtin command
     to specify conditions for the use of particular tags.  For example:

          zstyle -e '*:-command-:*' tag-order '
              if [[ -n $PREFIX$SUFFIX ]]; then
                reply=( )
              else
                reply=( - )
              fi'

     Completion in command position will be attempted only if the string
     typed so far is not empty.  This is tested using the PREFIX
     special parameter; see *Note Completion Widgets:: for a
     description of parameters which are special inside completion
     widgets.  Setting reply to an empty array provides the default
     behaviour of trying all tags at once; setting it to an array
     containing only a hyphen disables the use of all tags and hence of
     all completions.

     If no tag-order style has been defined for a context, the strings
     `(|*-)argument-* (|*-)option-* values' and `options' plus all tags
     offered by the completion function will be used to provide a
     sensible default behavior that causes arguments (whether normal
     command arguments or arguments of options) to be completed before
     option names for most commands.

urls
     This is used together with the the urls tag by functions
     completing URLs.

     If the value consists of more than one string, or if the only
     string does not name a file or directory, the strings are used as
     the URLs to complete.

     If the value contains only one string which is the name of a normal
     file the URLs are taken from that file (where the URLs may be
     separated by white space or newlines).

     Finally, if the only string in the value names a directory, the
     directory hierarchy rooted at this directory gives the
     completions.  The top level directory should be the file access
     method, such as `http', `ftp', `bookmark' and so on.  In many
     cases the next level of directories will be a filename.  The
     directory hierarchy can descend as deep as necessary.

     For example,

          zstyle ':completion:*' urls ~/.urls
          mkdir -p ~/.urls/ftp/ftp.zsh.org/pub/development

     allows completion of all the components of the URL
     ftp://ftp.zsh.org/pub/development after suitable commands such as
     `netscape' or `lynx'.  Note, however, that access methods and
     files are completed separately, so if the hosts style is set hosts
     can be completed without reference to the urls style.

     See the description in the function _urls itself for more
     information (e.g. `more $^fpath/_urls(N)').

use-cache
     If this is set, the completion caching layer is activated for any
     completions which use it (via the _store_cache, _retrieve_cache,
     and _cache_invalid functions).  The directory containing the cache
     files can be changed with the cache-path style.

use-compctl
     If this style is set to a string _not_ equal to false, 0, no, and
     off, the completion system may use any completion specifications
     defined with the compctl builtin command.  If the style is unset,
     this is done only if the zsh/compctl module is loaded.  The string
     may also contain the substring `first' to use completions defined
     with `compctl -T', and the substring `default' to use the
     completion defined with `compctl -D'.

     Note that this is only intended to smooth the transition from
     compctl to the new completion system and may disappear in the
     future.

     Note also that the definitions from compctl will only be used if
     there is no specific completion function for the command in
     question.  For example, if there is a function _foo to complete
     arguments to the command foo, compctl will never be invoked for
     foo.  However, the compctl version will be tried if foo only uses
     default completion.

use-perl
     Various parts of the function system use awk to extract words from
     files or command output as this universally available.  However,
     many versions of awk have arbitrary limits on the size of input.
     If this style is set, perl will be used instead.  This is almost
     always preferable if perl is available on your system.

     Currently this is only used in completions for `make', but it may
     be extended depending on authorial frustration.

users
     This may be set to a list of usernames to be completed.  If it is
     not set or the string on the line doesn't match any of the strings
     in this list, all usernames will be completed.

users-hosts
     The values of this style should be of the form `USER@HOST' or
     `USER:HOST'. It is used for commands that need pairs of user- and
     hostnames.  These commands will complete usernames from this style
     (only), and will restrict subsequent hostname completion to hosts
     paired with that user in one of the values of the style.

     It is possible to group values for sets of commands which allow a
     remote login, such as rlogin and ssh, by using the my-accounts tag.
     Similarly, values for sets of commands which usually refer to the
     accounts of other people, such as talk and finger, can be grouped
     by using the other-accounts tag.  More ambivalent commands may use
     the accounts tag.

users-hosts-ports
     Like users-hosts but used for commands like telnet and containing
     strings of the form `USER@HOST:PORT'.

verbose
     If set, as it is by default, the completion listing is more
     verbose.  In particular many commands show descriptions for
     options if this style is `true'.

word
     This is used by the _list completer, which prevents the insertion
     of completions until a second completion attempt when the line has
     not changed.  The normal way of finding out if the line has
     changed is to compare its entire contents between the two
     occasions.  If this style is true, the comparison is instead
     performed only on the current word.  Hence if completion is
     performed on another word with the same contents, completion will
     not be delayed.

