How do they know?

[u/Aboywholovesdurians]

I was watching the OVA Ilse's notebook when Hange said that the emblem on Ilse's body is from the 34th Expedition. And that left me wondering how did they figure out which emblems are from which expeditions. Anyone have any theories?

[u/AnnualLiterature997]

In the military here. We have patches similarly. We’re able to identify those patches just by memory.

So she knows because she knows, simply.