What does SpaceOops::filter_id_type do?

I’m asking this question because, after doing a search, I’ve only seen 2 possibilities for it’s value: ID_GR and 0

Am I understanding this right, there are only 2 possible values for filter_id_type ?

Thanks

When you go to the Outliner > Blender File view, it’s the button in the top right corner to filter by type.

Oh ok. I got it now. Thanks