How delivery quantity of STO affected by avalilability check defined in SD?

Question

Hi all,
Under SPRO purchasing, setup STO, I setup document type and shipping point to use delivery type NL and checking rule of availability check as "RP".
I thought the checking group "02" in material master  and  checking rule "RP" here will define availibility check when create delivery for STO with VL10B.
Apparently, the other checking rule "B" was actually used, since the changes to the "avalability checking control" "02+B" took effect. I have safety stock of quantity 5, changing the availibilty check  "02+B" to "include safety stock", I got 5 more available. Changes to "02+RP" has no effect at all.
There must be another place where "B" was defined, which overwritten the setup in SPRO purchasing, setup STO.
So where the setup could be?
Thanks!
Regards
Simon

Answer 1

Thank you Jürgen!
This notes is about how to use the availible quantities at different time though.
The problem I am having now, it the at the same place of SPRO:
-->Materials Management -->Purchasing -->Purchase Order -->
Set up Stock Transport Order -->Assign Delivery Type and Checking Rule,
Another field: CRI: Checking rule for availablity check "RP", it was not used, the other rule "B" was actually used, that must have been setup somewhere else, it should be in SD, just couldn't figure where.
In "avalability checking control" "02+RP", I have "Include safety stock" checked off.
In STO, I tried the option "C" in the notes you recommanded, the quantity committed is 13, whichi is correct, I have inventory 13. Also have safety stock 5 in material master, the delivery that was created only has quantity 8.
In  "avalability checking control" "02+B", I didn't  check off "Include safety stock".  to test, after I checked off it, Then I got delivery of quantity 13.
So "B" must be setup somewhere in SD, for the delivery.
Regards
Simon