diff --git a/Modules:Setup.md b/Modules:Setup.md
index 8be255e..18d54e6 100644
--- a/Modules:Setup.md
+++ b/Modules:Setup.md
@@ -130,7 +130,12 @@ The GameItemLoader looks for the `<module root>/items/itemid.csv` for the list o
 
 The Item ID for the items will be `item@<module name>:<id defined in the csv>` e.g. `item@basegame:1`
 
-TODO describe the csv but not the GameItem
+##### itemid.csv
+
+Every item's id-classname pair is defined on the csv file with following columns:
+
+- id: ID of this item
+- classname: the full classname of the item which extends `net.torvald.terrarum.gameitems.GameItem` 
 
 #### GameMaterialLoader