The manual says I can type #+ and then hit M-tab to get the list of completions.  In my case, flyspell-mode had stolen that key binding so I disabled flyspell-mode.

There are 100 #+ candidates.  Is there a nice place that lists them and documents each one?  So far, I’ve yet to find one.  It is sometimes nice to browse through such a list just to become familiar with what is possible.

Thank you,
Perry