Binary/boolean set-symbol values may be used freely in arithmetic statements, often very conveniently. Thus Robert Rosenberg's IFy logic becomes
|&length_in setb (t'&L ne 'O') |&source_in setb (t'&SOURCE ne 'O') |&target_in setb (t'&TARGET ne 'O') |&nparms seta &length_in+&source_in+&target_in | . . . In principle, undiagnosed misuse of a macro should be impossible. In practice, this ideal can be approached but never quite achieved. John Gilmore, Ashland, MA 01721 - USA
