Metacat

The xml_documents.docid field is currently used to store the metadata identifier
for all xml documents. However, our revision system creates new versions of the
document each time a UPDATE or DELETE is performed on the document.
Consequently, we need a "revision number" field in the "xml_revisions" table in
order to differentiate the various revisions. We also need a way of specifying
the revision number in the various xml formats used to pass the metadata
identifier, such as the meta_file_id fields, and in the eml-package
specification.

Finally, this has implications for the use of the docid in uniquely specifying a
document before and after it has been revised.

xml_documents.docid    xml_revisions.docid/rev
Old version        NCEAS:1            --
New version        NCEAS:1            NCEAS:1/1

So, in fact, when werefor to the old version as NCEAS:1 in a document, and then
later revise it and refer the the revision as NCEAS:1, we are generating
ambiguity.

This is closely tied to the lineage/version metadata issue that
schild@nceas.ucsb.edu is tackling. See Bug #144.