While many items can be added to players, many cannot. For example, I've tried adding a Big Hiking Bag and none of the following commands are working (but the same format works perfectly for adding Base.Axe for example):
/additem "mrpetrov" "Base.Bag_BigHikingBag"
/additem \"mrpetrov\" \"Base.Bag_BigHikingBag\"
/additem mrpetrov Base.Bag_BigHikingBag
/additem "mrpetrov" "Base.BigHikingBag"
/additem \"mrpetrov\" \"Base.BigHikingBag\"
/additem mrpetrov Base.BigHikingBag
Whenever I try one of these commands, the console just returns the description for /additem.
Similarly, many items can be added, but many cannot - this is just one example. I think it's related to items which have an underscore in their ID, but not 100% sure.
P.
