SocketContent

[Rochet2]

http://collab.kpsn.org/display/tc/item_template#item_template-socketContent

What is the SocketContent column in item_template exactly?
Its 0 for all items in the database:

select * from item_template where socketcontent_1 <> 0 or socketcontent_2 <> 0 or socketcontent_3 <> 0;

and it is not used in server code anywhere except for loading it to memory and then sending directly to client with other item template data.
The wiki says "Amount of Gems of SocketColor1", but there is no visual impact from what I can see when I use different values.