keylset listvar key value ?key2 value2 ...?
Set the value associated with key, in the keyed
list contained in the variable listvar, to value.
If listvar does not exists, it is created. If key
is not currently in the list, it will be added. If
it already exists, value replaces the existing
value. Multiple keywords and values may be speci-
fied, if desired.
This command is provided by Extended Tcl.