The Open Group, OASIS and OMG have published a concerted document about the open SOA standard landscape and the relation of the myriad of standards in this area.

In their own words the document:

[...] explains and positions architectural standards for SOA reference models and ontologies, reference architectures, maturity models, SOA modeling languages, and open standards work related to the topic of SOA governance. It also outlines the agreement on core SOA and SOA governance concepts.
This document is intended to serve as a guide to the reader to help differentiate and select specifications appropriate to their needs.

Direct link: Navigating the SOA Open Standards Landscape Around Architecture.