You're using macro substitution anyway, why not build the whole FOR condition?

lcForCond = iif(empty(lcValue), [isdigit(allt(ctag))], [inlist(cTag,] + lcValue + [)] )
BROWSE FOR &lcForCond

>When trying to run this code:
>

>brow for iif(empty(lcValue),isdigit(allt(ctag)),inlist(cTag,&lcValue))
>

>I get "Function argument value, type, or count invalid". In this instance the value of lcValue is empty. It seems like the IIf() is still evaluating the code. cTag is a field. Any ideas? I have to leave but will check back later.
>