Extract enumeration collection of RTC

Yes it is possible. Pick a work item in the project area of your interest, say work item 123. You can get all the enumerations from this URL.

https://<server>:<port>/ccm/rpt/repository/workitem?fields=workitem/workItem[id=123]/projectArea/enumerations/(id|literals/*)

If you don't filter on the work item (using [id=123]), similar content will be produced for the first 100 work items (in random order), which is definitely what you want.
You can find more information in this article.
https://jazz.net/wiki/bin/view/Main/ReportsRESTAPI

Sorry. I wanna filter enumeration by ProjectArea, not workitem.

Is it possible?