If you assign an individual number to the cover/title page, it is taken as
an integral part of the portfolio as a whole (as opposed to unimportant
packaging material).  In addition, if the cover is separated from the
lithographs, you know by looking at the number that there are more
components to search for.

>Our registrar is about to catalog a portfolio of Ben Shahn lithographs
and
>has encountered two different numbering systems in use by other museums.
>We'd like to get an idea of what's standard. The lithographs are enclosed
>in a linen cover, which is stamped with an image and the title page has
>been folded  in half so that it serves as a cover for the 24 loose
>lithographs in the portfolio. She plans to individually number the
>lithographs, but is it common practice also to assign a separate catalog
>number to the cover and title page or simply to label them with year and
>lot number (ex. 1996.7) and then just give the lithographs indiv. numbers
>(1996.7.1, 1996.7.2 etc.)?. Thanks for your help
>
>Margaret Bullock
>Montgomery Museum of Fine Arts
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