Is there a way to show where a metadata record came from in OAI, apart from analyzing OAI identifiers?
There is a “provenance” container that can be included in an OAI “about” which will clearly indicate from where the metadata record came. See http://www.openarchives.org/OAI/2.0/guidelines-provenance.htm. OAI identifiers, especially those that follow the recommended OAI-identifer format (http://www.openarchives.org/OAI/2.0/guidelines-oai-identifier.htm) may be analyzable, but they may not be analyzable, as OAI identifiers do not need to adhere to this format.