hs10, hs20... what addon does this?

[xen32]

Every now and then I see in /s chat from some random person "hs10", "hs20", "hs0" and it is definitely automated response to something... but to what? And what does it mean? I've asked what is this at least last 20 times I've seen this, no one ever responded.

It is definitely not related to heavy sacks, I've seen this everywhere: in Vivec crafting hub, Cyrodiil Keep, Trial boss, in random towns and such.


Anyone knows?