Z39.50. OASIS has released a position paper and is seeking comments. Search Service Interoperability edited by Eliot Christian.

Governments are recommended to enhance interoperability among their networked systems by adopting a common search service. The search service should be based on the ISO 23950 international standard that features a high degree of interoperability across many communities of practice and types of data and information holdings. Governments should implement the search service as a supplement to other search mechanisms, as these may be required for reasons other than broad scale interoperability.

Z39.50 is a fine standard, however, I think OAI-PMH should also be considered. It does get a mention on page 5. [Catalogablog]
10:44:35 AM