The terms <user-defined fields> and <custom fields> refer the same thing – fields defined by a user that apply to a contact in addition to the standard Outlook fields.
However, for ease of reference, the term <custom fields> is used for those user-defined fields that are defined as part of a custom form.
One specific item to be aware of is that when a custom form is designed for a given contact folder, any user-defined fields added as part of the custom form will also be added to the folder’s “User-defined fields in folder” list which is essential if those UDF’s are to be used in any custom view. If this same custom form is simply published to another contact folder on either the same or other computer, the user-defined fields do not get added to the <User-defined fields in folder list>.
Some other essential differences between <custom fields> defined in a custom form and <user-defined fields> used with contact items using the standard Outlook form (messageclass – <IPM.Contact>) some of which are:
- UDF’s are unique to the custom form for which these were defined. Any additions/deletions to UDFs should always be made using the Outlook forms designer.
- Custom fields will always appear for any contact whether or not any data is contained in the field however those fields can only be used in an Outlook view if the fields appear in the folder’s “User-defined fields in folder” list
- The custom field data will not be accessible if the assigned custom form (message class) is changed for the contact item. However, if data was added to custom fields and the message class for the item is changed, this data can be recovered by changing the message class back to the original custom form used to create the data.
- Custom fields should not be defined for and/or reference a standard Outlook field during the design phase. A custom field that references a standard Outlook field just adds unnecessary baggage to the form presenting the possibility of an issue to be encountered with 3rd party products
- User-defined fields should never be added to contact item created with a custom form since this will cause it to become a one-off item. Similarly, a custom field should never be deleted from the <user-defined fields in this item> group. The custom form should be modified to add/delete fields as required and then re-published. Any changes to the custom form will immediately apply to all the contact items assigned to it.
- A contact folder can contain contact items created with different custom forms. Changing the default MessageClass (custom form) for the folder does not alter the message class for any pre-existing contact item.
- If a custom form has undergone heavy editing with extensive changes particularly in the area of adding/deleting fields to the form, it would be good practice to re-create a clean final form that will be used in production. Experience has shown that the custom forms with extensive editing always seem to be involved when problems occur.
- Do not forget to keep a backup of your custom form should the need ever arise. It’s a very quick process that simply requires a new blank contact using the newly created form to be opened and from the file menu –> Save As –> select .OFT as the file type