deprecation

This appears to be what the IETF defines in this area:

/*

If a definition is "deprecated" then it simply means that it's no  
longer of major importance...and need not be implemented except for  
backwards compatibility with older agents that do implement them.  It  
also means that at some point in the future those definitions may have  
replacements and the old definitions will be made "obsolete".

If it's "obsolete" then it usually means that are new definitions that  
replace the old ones and the new ones should be used in any new  
implementation (and, if possible, old implementations should be  
brought in line with the new definitions).

*/

...my thinking is that whichever way we go we will need to have  
explicit definition within our spec that defines those things being  
teed up for replacement and those that are no longer valid.

b