def setup(app):
    app.add_crossref_type(
        directivename = "setting",
        rolename      = "setting",
        indextemplate = "pair: %s; setting",
    )
    app.add_crossref_type(
        directivename = "sig",
        rolename      = "sig",
        indextemplate = "pair: %s; sig",
    )
    app.add_crossref_type(
        directivename = "state",
        rolename      = "state",
        indextemplate = "pair: %s; state",
    )
    app.add_crossref_type(
        directivename = "control",
        rolename      = "control",
        indextemplate = "pair: %s; control",
    )