Okay, my apologies, I didn't read far enough. It does say it'll do that. Although it may be an error in Nasm, I'd treat it as an error in the documentation. Seems to me like an "obviously wrong" thing to try to do.
Do you have something in mind for this? What would you like it to expand to?
mov ax, 1 + a(3)
?
Straighten me out here...
Best,
Frank