There is a setting for an item attribute that determines whether, and how the attribute is copied when a new revision of an item is created. The options are:
Stored per revision, default as specified: when a new revision of an item is created, Dimensions CM does not copy the attribute values from the previous revision but initially sets them to the specified default value according to the Default Value above. You can subsequently override them for a specific revision.
Stored per revision, default to previous revision: when a new revision of an item is created, Dimensions CM initially sets the attribute values to those from the previous revision, but you can subsequently override them for a specific revision.
Same for all revisions: Dimensions CM sets the attribute values for all revisions of the same item to the same value. When you update the value of an attribute for any revision, Dimensions CM will also update that attribute for all other revisions.
This is determined when an attribute is assigned to an item type. See Assigning an Attribute to an Object Type for details of how to do this.