Macro match_arg_wording 

macro_rules! match_arg_wording {
    (not_character) => { ... };
    (not_scalar) => { ... };
    (not_a_choice) => { ... };
    (or) => { ... };
    (alias_for) => { ... };
}

The words of a match_arg argument error, shared by the wrappers preamble’s .miniextendr_match_arg / .miniextendr_match_arg_several (crate::registry::ARG_CHECK_HELPERS, built with concat!) and MatchArgError::arg_error, so R and Rust word these errors from one source (#1741). The generated conversion of a match_arg type words its error with arg_error too (#1767). or and alias_for are the words of the clause naming the listed aliases (listed_aliases_clause, #2148), which the wrappers writer renders in Rust and passes to the R helpers as their listed argument. It expands to string literals.