Specifications

Simple Object Access Protocol (SOAP) 1.1
The W3C Note on the Simple Object Access Protocol 1.1 submission.
http://www.w3.org/TR/SOAP/

Simple Object Access Protocol (SOAP) 1.2
W3C Working Draft 9 July 2001. SOAP version 1.2 is a lightweight protocol for exchange of information in a decentralized, distributed environment. It is an XML based protocol.
http://www.w3.org/TR/soap12-part1/

SOAP Reference at Zvon
A complete reference which can be downloaded for off-line use.
http://www.zvon.org/xxl/soapReference/Output/

XML Protocol (XMLP) Requirements
Describes the XML Protocol Working Group's requirements for the XML Protocol (XMLP) specification.
http://www.w3.org/TR/xmlp-reqs