Can I recover the value 5 from the macrovariable Y ?
I thought &&Y.. would do the trick but it resolves to "X."
OK, I have found the answer : add a third ampersand
I just don't understand the logic behind this.
The macro compiler removes duplicate &, "pairwise". In your case:
&& resolves to &.
&Y resolves to X.
Leaving &X, which resolves to 5.
Ok, that makes more sense now.
Can be done, how depends on your application.