I keep several calendars for differetnt appointments and they are always changing. I could not live without my handy little roll of roll-on white-out tape with the blue reel and nozzle. It's easy t roll on easy to write on and you can correct the same entry over and over. It covers itself perfectly. Covers one line of type. And it. doesn't show up in photocopiesI. I buy it by the dozen rollls - which are very long lasting by the way. I sound like a commercial but it's all true.