Macro fc_modifier 

macro_rules! fc_modifier {
    (
        $(#[$meta:meta])* $vis:vis enum $name:ident for $bem:ident {
            $(#[$default_doc:meta])* $default:ident => None,
            $($(#[$variant_doc:meta])* $variant:ident => $suffix:literal),* $(,)?
        }
    ) => { ... };
}

Declare a modifier vocabulary once, including parsing and coverage enumeration.

The for argument is the component’s BEM constant, so its prefix is not duplicated. Empty input parses as the bare variant.