When the switch is defined as a list of two entries, the first one is
the switch name and the second one is the switch value. If \fB-switch\fR
is used several times for the same argument, all switches are added
as potential switches. On call-site, the related switch value will be
set on the argument if one of the switch names is used.
See \fBNAMED ARGUMENTS HANDLING\fR below for details on named arguments.
.TP
\fB-upvar \fIbool\fR
\fB-upvar \fIlevel\fR
.VS
If \fIbool\fR is set to true, this will cause the related variable,
rather than taking the parameter value, to become an alias
to the variable in caller's scope corresponding to the parameter value.
When defined, this will cause the related variable, rather than taking
the parameter value, to become an alias to the variable in the frame
at level \fIlevel\fR corresponding to the parameter value. \fILevel\fR
may have any of the forms permitted for the \fBupvar\fR command.
This specifier is incompatible with the \fB-switch\fR specifier.
.TP
\fB-varname \fIvarname\fR
.VS
Defines a new variable named \fIvarname\fR which will be added in the
procedure with the original value of the parameter. This is mostly used
with \fB-upvar 1\fR to access the name of the linked variable.
.VE
.SS "NAMED ARGUMENTS HANDLING"
.VS
.PP
Named argument are arguments defined using the \fB-name\fR or \fB-switch\fR
extended argument specifiers. They have a special handling on call-site.
All contiguous named arguments, called named group, are handled together,