Sqlite has some complicated rules about what is allowed in a column default value:

A constant expression enclosed in () is allowed. A constant expression may contain operators recognised by sqlite (see its documentation for details), quoted strings, numbers, and calls of built-in scalar functions. Calls to built-in functions are evaluated when a row is created, so they can in fact return non-constant results, for example random().

A bare or quoted identifier (using any of the quoting methods allowed by sqlite) is allowed, and will be treated as a string.

A quoted string is allowed, optionally preceded by a plus or minus sign. If the sign is present the string will be converted to a number using sqlite's normal rules (which may result in zero) and negated if the sign is a minus.

An integer or a floating point number is allowed, optionally preceded by a plus or minus sign.

GENERATED column values (a new feature in sqlite) are not yet supported by sqliteman.