Macro vocabulary 

vocabulary!() { /* proc-macro */ }

Define an open vocabulary in STIX. Open vocabularies have a set of standard-defined values and allow arbitrary additional values.

Example

vocabulary!(
    /// Doc comments carry through, as do other attributes.
    #[cfg(not(windows))]
    ImplementationLanguage = [
        applescript,
        bash,
        c_plus_plus = "c++",
        c_sharp = "c#",
        x86_32,
        x86_64
    ]
);