Are you sure it is AIX? I have not seen it on a normal AIX box...the same with searching for it with the which_fileset... perhaps it is a created program?
I have seen pmenu in SAS? Pull down menus.....and Also in Java I believe?
Smit allows you to write custom menus, but I don't think they are called pmenu,
I may be wrong
Sorry ....Maybe someone else knows?
#-)