Costco Hearing Aid Tests: What are the "U" lines?

A few years ago, I took a hearing test from Costco to see if I needed hearing aids:

The top lines are clear enough (level of hearing loss, by left/right ear, through air or bone conduction).

But there are two additional lines at the bottom with U symbols (or perhaps ∪), and I can’t find any information online about what they are supposed to represent. (Certainly I don’t have hearing loss anywhere near the 100+ dB level)

Does anyone know?

I’ve poked around a bit and this link talks about ‘other symbols’

One of which is UCL which is for Uncomfortable Level

I think that might be it.

Thank you! That makes sense, and some random reddit threads from Costco audiologists seem to confirm they do those tests.

I don’t remember them ever having played loud sounds for me (and seems like 100 dB+ would be deafening?), but it was a few years ago, so maybe I just forgot. Or maybe the person just put in fake numbers because I didn’t need hearing aids anyway.

Anyhow, thank you! Mystery solved.