I have two Macs using 10.6.8 and if I add a calendar to iCal on either Mac I have the choice of adding a calendar (or Calendar Group) "On My Mac" or in my "CalDev Calendars". I do have most of my calendars syncing via CalDev to my server. When I go to my 10.8.2 server to add a calendar, I only have an option to add a calendar to "CalDev Calendars" with no option of adding a Calendar Group.
How do I add a calendar (or Calendar Group) "On My Mac" and not in "CalDev Calendars" in Mountain Lion iCal?
Ok I solved my own problem.
I only had "CalDev Calendars" on my server iCal, so I un-enabled the calendar account in iCal preferences, then added a calendar and an "On My Mac" calendar appeared. I re-enabled my "CalDev Calendars" in preferences and now I have both "CalDev Calendars" and "On My Mac" calendars on my server iCal. This also returned the menu items missing under "file" menu.