Instanciation of net. Differents kind of nets are listed below :
SignalIn : Creation of an input port
SignalOut : Creation of an output port
SignalInOut : Creation of an inout port
SignalUnknown : Creation of an input/output port which direction is not defined
TriState : Creation of a tristate port
CkIn : Creation of a clock port
VddIn : Creation of the vdd alimentation
VssIn : Creation of the vss alimentation
Signal : Creation of an internal net