Macro csl_vocab 

macro_rules! csl_vocab {
    (
        $(#[$meta:meta])*
        $vis:vis enum $name:ident { $($(#[$variant_meta:meta])* $variant:ident => $text:literal),+ $(,)? }
    ) => { ... };
}

Generate a closed CSL vocabulary enum with as_str / from_csl / Display.

Each variant maps to its exact CSL string form (e.g. "article-journal", "DOI"). from_csl is the inverse and returns None for unknown strings.