Lists come in a variety of forms in the default version of OCD:

1. Lists with fixed values where the user cannot type in a different value, but which can be edited in preferences -> database. I.e., Category on the general tab of album properties

2. Lists where the user CAN type in a new value, and this value is added to the drop down list. Names of band members on the Musicians tab, for example.

3. Lists with fixed values where the user can enter a new value, but the new value is not added to the drop down list although the list can be edited in preferences -> database. Format is an example of this.

4. Lists where the user can type in a new value, but this new value is not added to the drop down list AND the list cannot be edited in preferences. Roles on the Musicians tab is the most notorious example of this.

It is not clear to me why all lists don't function the same way. In particular, it is not at all clear to me why the Roles list limited when it should behave like either type 2 or type 3.