X/Open XA Interface

I am looking for information on X/Open's XA interface. Here's what I do know: XA is a standard API to resource managers, e.g., a DBMS. It is intended to be used at the system level, not the user level, by transaction processing monitors (eg, CICS/6000, Encina, Tuxedo). It supports two phase commit (2PC) and some resource monitoring, load balancing, and scheduling controls. What I don't know are the details. I am especially interested in the resource monitoring, load balancing, and scheduling controls. What services are part of the standard? What services are implemented by any particular dbms? The packages that support XA, according to CICS/6000 docs, are: - IBM DATABASE 2 AIX/6000 Version 1.1 - Oracle Version 7.0.13 or Version 7.0.15 or Version 7.0.16 or Version 7.1.3 - Sybase Version 10.0.1 - Ingres 6.5 - Informix Version 5.02 or Version 5.03 Any information regarding XA in these packages, or in general, would be greatly appreciated. I don't want to be forced buy the official standard... --Kevin P.S. As usual, be sure to follow-up to all the newsgroups, but if nothing else, be sure to reply in comp.databases, which is where I'll be looking :-)