Neither pos nor vec are "list operators". I say this because I don't see "pos LIST" nor "vec LIST" in the "Synopsis" section of their respective documentation entries.

I also checked     perl -e "print prototype('CORE::chomp')" for several of the items, but that appears to be a rather imperfect test.

Perhaps it is the "chop VARIABLE" and "chomp VARIABLE" entries in their synopsis sections that (indirectly) explain this behavior?

        - tye (but my friends call me "Tye")