CCK fields revisions (D6)
CCK stores values against the vid, so you should be able to see the history of your fields (you can look in tables like content_% to check that the raw data's there). Otherwise a revert would be fairly useless for most situations involving fields. Can you confirm the results of the following?


Create new content type with revisions turned on.
Add text field.
Create a node of this new type (add some text to the field).
Edit the node and update the title, body and field.
Revert the node to its first state.