Hi
All the item type journals in NAV end up going through the item journal table which is why you see the consumption as a type
The reason behind the system having the different interfaces, like "Consumption Journal" is so that the system can ask for the correct fields to be filled in and run the correct business rules checks on the journal before it posts
Although it is possible to "Break" the item journal so that it will allow users to post consumption in the item journal I would recommend against this as you will loose some of the validation and checks, this will result in all sorts of things breaking later on in the production process
Cheers
Nev