 work until the entire document
    has been parsed and possibly transformed to some extent.  So the directive
    code leaves a placeholder behind that will trigger the second phase of its
    processing, something like this::

        <pending ...public attributes...> + internal attributes

    Use `document.note_pending()` so that the
    `docutils.transforms.Transformer` stage of processing can run all pending
    transforms.
    Nrn