> While I appreciate the distinction between license and classification, does it really matter if a piece of software is "in the public domain" if its very existence and content is classified and non-disclosable?

If the entire work is, less so than if it was disclosable (although there are laws governing the government use of copyright protected work, and arguably there is a benefit to the public interest if the vendor has provided and open source license even if the work is not publicly disclosable.)

But practically, classification and, perhaps even moreso, the other exceptions to FOIA would often apply to limited portions of software systems rather than whole systems, as is often the case with other materials covered by FOIA.