In general, CTX will conform to Cisco policy of supporting up to two major releases backwards.
 
Our versioning scheme will be invocation context-based.  That is, we will include the version number in the URL path for subsequent versions.  For example, the initial version of the CDR API will be located at a URL that looks like this:
 
http://1.2.3.4/ctxapi/api/cdr
 
Our next version will be located at a path something like this:
 
http://1.2.3.4/ctxapi/api/v2.0/cdr
 
In this example, if CTX is currently at version 2.0, a client designed to work with the initial version can continue to use the first URL path above.  CTX will be able to differentiate these down-rev requests and respond in a backward compatible way.