Availability check

I've configured the following scenario in our R/3 (4.7) system. I am using a cash sales order ZBV (copy of BV) without the delivery process. It's required that the order quantity in the order updates the stock level.

According to the documentation the MRP type and the item category determine the requirement type.
MRP Type Z1 and item Category ZBVN use Requirement type 031

The scope of the availability check is determined by the checking group and checking rule
The checking group is 01 - Daily requirements but I don't know which checking rule is determined by the system. Documentation says that it is determined automatically by the system. Which one would be used by cash sales order without a delivery process?

Can you have a look at my config and see if I'm missing something?

Item Category ZBVN

Schedule Line

MRP type in the material master is set to Z1

MRP Type Z1 and item Category ZBVN use Requirement type 031

Requirement type 031 is assigned to Requirement class 031

Checking group 01 is assigned to the material

Which checking rule is being used by the system for my scenario?

MMBE

MD04

CO09