What is " Additional Map Currency Item " Mod on craftable watchstone?

In poe wiki, there are as follow

https://pathofexile.fandom.com/wiki/Currency

1 Currency items
1.1 Functional currency
1.2 Shards and fragments
1.3 Essences
1.4 Prophecies
1.5 Vials
1.6 Harbinger currency
1.7 Perandus coins
1.8 Delve currency
1.8.1 Fossils
1.8.2 Resonators
1.9 Oils
1.10 Catalysts
1.11 Discontinued currency items

Just wondering, can't seem to find any information related to map currency.

By personal experience, so take with a grain of salt:
-Chisel
-Sextants
-Horizon Orbs