def setup(app):
    app.add_crossref_type(
        directivename = "setting",
        rolename      = "setting",
        indextemplate = "pair: %s; setting",
    )
    app.add_crossref_type(
        directivename = "signal",
        rolename      = "signal",
        indextemplate = "pair: %s; signal",
    )
    app.add_crossref_type(
        directivename = "command",
        rolename      = "command",
        indextemplate = "pair: %s; command",
    )
    app.add_crossref_type(
        directivename = "reqmeta",
        rolename      = "reqmeta",
        indextemplate = "pair: %s; reqmeta",
    )