I activated the Custom field. When I click "customize," one of the options is "activate user-defined field." I have many UDF's in this address book, but the only choice is *UseAlternateForm.

Am I supposed to be able to select other UDF's?

What does it mean to "activate" a UDF? Most of mine are simply data fields (checkboxes, text boxes, etc.).

Is there any way to use this feature to do a mailto:email1 for the entry? Or to do some other command / run a program that is based on some data in the entry (like open a Word Document titled LastnameFirstname.doc or something).