Use this tag for questions related to cfajaxproxy, a tag that provides the ability to create a JavaScript proxy "class"
Quoting its GitHb page:
The cfajaxproxy tag provides the ability to create a JavaScript proxy "class" which can be used to create proxy objects which in turn proxy for a ColdFusion CFC back on the ColdFusion server. This means JavaScript code can call methods on the JavaScript object, which will - in effect - execute functionality on the ColdFusion server.
Note that ajax and coldfusion are tags that are usually used together with cfajaxproxy.