All reports of doc-base-invalid-document-field for the archive. The extended description of this tag is:
The Document field should consists only of letters (a-z), digits (0-9), plus (+) or minus (-) signs, and dots (.). In particular, uppercase letters are not allowed.
Refer to Debian doc-base Manual section 2.2 (Document IDs) for details.
This tag has not been emitted in any package tested by Lintian.