Interdependent Fields
This video tutorial provides a great solution for any calendar or scheduling application. I found this technique while reading Mikhail Edoshin's excellent blog about his FileMaker solutions. This technique is about leveraging the auto-enter fields more than you may have in the past.
So, while standing on the shoulders of giants, (Mikhail and Alexander) I was able to implement an enhanced version for creating an excellent date-based start/duration/end type of technique. If you have the need for any given field to exert control over any others, when changed, then watching this video will teach you what you need to know!