My code for the custom fields presentation

As promised, here is the code I used. For the PowerPoint presentation I need to get approval, so wait for it.

The code has three samples of custom field types - one is a prime number validation field type (allows people to type only prime numbers), one is a date validation field that checks two other fields that the end date is after the start date (this is a good example for creating custom properties for the custom field) and the last is a sample how to create a custom look and feel for a custom field, without compiled code - just XML definition (CAML) in the renderpattern section. have fun!