I've noticed that on an advanced find for CI you can search on "user person" and on "user organization".
When I try this, I always get zero records found (eg User person is not empty). However, I'm sure that there are CIs that are used by persons or organizations.
Also, I haven't seen these fields in advanced find before. So I'm wondering, have I been blind for several years or are these new (not working) options since one or the other SP or am I failing to see the true usage of those fields.