When I still used Emacs Diary as my default organizer I valued its ability to mark items on the calendar. One could also make an entry that was NOT so marked by placing an ampersand before the entry. The entry would appear in the diary but would not be marked in the calendar. I have since switched to org-agenda and have set up calendar (and also calw-org) to display my org-agenda files. However, there are certain appointments I would like to hide from being marked in the calendar. How does one do this with an org-file?