Note When others add you as an attendee to a meeting, your Free/Busy information in the Meeting Planner or Scheduling Assistant will show you as Busy or Out of the Office, not Outside of working hours.
Times blocked out as Busy show as a blue bar. Times set aside as Out of Office appear as purple or violet bars. The times that are scheduled as Outside of working hours normally show up as gray bars or areas. The screenshot below shows an example of each, including Tentative, which appears as a bar with diagonal, striped bars or hash marks.
In the screenshot above, the 11am appointment or meeting is set to Tentative. The 1pm time slot shows Out of Office for 1-hour. At 3pm, you see a meeting or appointment that is marked as Busy. Starting at 4pm, you can see the light gray area that normally indicates the times that are Outside of working hours.