This button is at the top of the Inspector when viewing any ItemObject
Selecting this button will open an Editor window with additional options which affect all ItemObjects of the same objectType.
Not all ItemObject options can be bulk-edited, but many can.
Allowed Item Attributes
Here you can quickly see the various Item Attribute types and objects, and whether none, all, or some of the Item Objects have them available. The Remove andAdd buttons will affect ALL of the Item Objects of this objectType.
This may make it easier to quickly ensure that the right ItemObjects have the right ItemAttributes available to them.