re "What does a document mean"

I've found a lot of interesting material on the topic
of documents and identity.

"Scrolling Forward: Making Sense of Documents in the Digital
Age", David M. Levy, isbn:1559705531, Arcade Publishing, 2001.
(http://www.scrollingforward.com). chapter 2, "What are documents."

David forwarded me a private copy of a chapter of a forthcoming
book, "Documents and Libraries: A Sociotechnical
Perspective"; among other references:

Buckland, M. K. (1997). What is a "Document"? Journal of the
American Society for Information Science, 48(9), 804-809.

Duguid, P. (1996). Material Matters: The Past and
Futurology of the Book. In G. Nunberg (Ed.), The Future
 of the Book, (pp. 63-102). Berkeley: University of California
Press.