This project is a Custom Field Type for use with SharePoint 2007 that provides regular expression validation on a text field. This particular method retains custom properties as well as having the ability to display those custom properties after they have been set.
The code in the project is based on the example Custom Field Type sample that is created when using WSPBuilder.
Also remember SharePoint custom field types are not deployed as features. You cannot activate or deactivate a field type. (You can hide it however) I have created this same type of project where it uses a Site Column which can be deployed as a feature. If interested in this please let me know and I'll put more work into it.Adding the new field:Testing the new field