Validation missing ? Set a standard (1) has 'generate' => identity (aka str) (2) no default (a) option => boolean (b) input => identity (3) default is boolean value (as Tcl understands it) => boolean (4) default is integer value => itenger (5) => identity Default missing (and required) ? (Required <=> There is no 'generate' either, and parameter is optional input) (1) list => empty list (2) => Default value supplied by the specified validation type.