Version 1.1 was the first publicly available version of the CTS protocol.
See the formal specification of the protocol:
Version 1.2.test adds a series of requests to the protocol to simplify the development of applications using CTS resources, and specifies support for requests using CTS URN notation. A draft specification is being reviewed as of August, 2005.
The main focus of planning for version 1.3 is support for TEI version P5. No draft specification has been produced yet.