title@level is an optional attribute. It allows only five values:
(analytic) analytic title (article, poem, or other item published as part of a larger item)
(monographic) monographic title (book, collection, or other item published as a distinct item, including single volumes of multi-volume works)
(journal) journal title
(series) series title
(unpublished) title of unpublished material (including theses and dissertations unless published by a commercial press)
We should clarify:
1. whether "j" is meant for titles of popular magazines in addition to titles of scholarly journals.
2. what value should be used for the title of a newspaper.
3. what value to use for the title of a series of conference proceedings. (While this is much like a journal, I think "s" is meant only for titles of monographic series.)