Lexical operator processing is performed on all source lines
    and macro expansion lines before any other assembler processing.
    Thus, macro invocations, assembler directives, and instructions
    are subject to lexical operator processing before normal
    assembler processing.

    Lexical operators are recognized and processed within string
    literals. Lexical operator processing is suppressed during macro
    registration in order that lexical operator evaluation may occur
    during macro expansion. Lexical operator evaluation is also
    suppressed for a range of text that is conditionally excluded
    with one of the .IF directives. In addition, lexical operator
    processing is not performed within a comment.