ejb-jar.xml: Required by the EJB specification. Describes the basic bean construction: cmp-field, cmr-fields and queries.
jbosscmp-jdbc.xml: Not-required. Used to declare exact database mapping for cmp-fields, cmr-fields, and queries. Used during tuning.
jaws.xml: The equivalent of jbosscmp-jdbc.xml for the old CMP 1.1 (only) persistence engine JAWS (not used in EJB 2.0).