Changing label values in NASM

Question

Once we assign a label using RESX or DX commands,(where X can be B, W, D, Q, T) is it possible to later assign a memory location to that label?

For eg, can I do something like,

mov label, X560h

Answer 1

Labels aren't in the final code (at least if you have a binary output). It wouldn't make any sense to change constants for the assembler while executing the code.

There are two ways to do it:

1. Undefine the label with %undef and redefine it
2. Write self-modifying code which changes all references to the label.

(I think that option 2 doesn't help you)

Answer 2

I think it's not possible. Labels cannot be changed.