On my Outlook 2007 calendar, I view multiple calendars in overlay mode. For example, I can see my boss's calendar overlaid on my own.
I also have some automatic formatting (Edit > Automatic Formatting) rules set up to highlight certain calendar entries. For example, meetings I need to attend stand out in a nice bright yellow.
I don't want the automatic formatting to apply to the other calendars. I can't seem to find any field that I can filter on to limit the rule to just my calendar.