In TRO, strategic calendar appointments are special and should be categorized with a color and maybe a context, depending on your tools.

Do Not Categorize Normal Appointments

Normal calendar appointments should not be categorized UNLESS the task manager can use calendar contexts to recommend tasks automatically. Categorizing normal appointments slows you down and could work against two TRO principles: 1) honoring all your appointments equally and 2) using your calendar as your time budgeting tool.