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Private/Public information is lost during export from MeetingMaker. It is also not possible to select either private or public events for export.
This means that all events will be exported as public. (bug report filed at MeetingMaker). You should manually set the events to private in your Google calendar after importing.
By default all staff calendars are shared (read-only) among staff. This means that there will be a short time that other people can see your private events.
If you do not want that, you should adjust the sharing policy of unshare your calendar prior to import, and change share it back again once you finished. This can be done in the Calendars tab in the Calendar Preferences.
If you are importing lots of historic events that include private ones, going through all events will be tedious. A middle-of-the-road strategy would be to make two different exports: one containing all historic events, and import those into a secondary calendar, which you do not share. Then export all future events to your main calendar. This way you will have way less events to adjust.
FYI, I filed a bug report for this issue at MeetingMaker. RFC5455 shows that it is trivial to implement this, it is just a matter of adding CLASS:PRIVATE to each exported private event.
Banners are lost
Banners are not exported at all. You should create events in Google Calendar as events with "Show me as Available".
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