I hashtag notes that I take with Emacs while I read books, articles, etc - humanities, mostly. I would like to know if Emacs can automatically build a list of hashtags that I enter (in a separate file, probably)? Also, can Emacs - reading from this hypothetical list - offer an incremental (or tab) autocompletion when I start to type the hashtag. I need this feature in order to have a consistent tagging. 

Thanx!