changes to numbering convention

Effective with this issue, accession identifiers issued under the present convention shall include a single-letter suffix to denote the analytical pass to which the metadata refers (A: pass A, B: pass B, etc.).
Records issued before the present revision retain their original identifiers; a concordance is being prepared for distribution to subscribing institutions.
Subscribers will be advised separately when the concordance is ready to consult.

— issued by the standing registrar, 1989-10-10