I think I've answered my question. Looking in HLASM Language Reference Chapter 9, there is a section "Evaluation of character expressions" following the description of the X2D built-in function. Item 2 in the Notes of that section states "A double ampersand generates a double ampersand as part of the value of a character expression."
So, C2B('&&') is correctly returning the value of two ampersands.
Regards, John Ganci
