>I like that, but the cursor/table may be unknown at design time. Is there a way to know the key field (or expression) of the current ALIAS?

There is ataginfo(). look for the primary key and key expression.
if ataginfo is not available, you could walk the tags with the older functions
tag(), tagno(), sys(14), sys(twentysomething), key() -
but I am not sure if you get primary/candidate info,
which is necessary for you

HTH

thomas