"C x A" is a combination of C and A. C, x, and A are defined once somewhere at the beginning of the paper/book. Should I take this (which doesn't actually hold

"C x A" is a combination of C and A. C, x, and A are defined once somewhere at the beginning of the paper/book. Should I take this (which doesn't actually hold in the general case) to mean that every document uses its own language? That isn't exactly good for readability. We certainly don't consider every software project to be written in its own language (and no, the semantics of C does not tell us what the dP function does).