SD material Determination based on availability check

For SD material Determination you can create a Substitution reason and on the Strategy field, the following info. is available:

Product selection in the background is performed on the basis of the availability check.

We want to have the material determination only in case on material shortage. We expect the Substitution reason to give us this functionallity. It does not hovever take the availabilty into account before substitution.

We thought the worse case is to create a ABAP which is linked to the "requirement" field in the Procedure (OV13).

Has anyone had the same requirement? Is this a bug or just incorrectly documented?

I also encountered this abnormally recently using material determination. In order to combat the problem, the first product substitution should be for the original material. I've illustrated this below:

Original Product: ABC
Substitutes: DEF, XYZ

In order to perform product substitution ONLY in the case of ATP failure for product ABC, structure the Material Determination record as follows:

Material Entered: ABC Substitutes: ABC
DEF
XYZ

There seems to be a devaition at availability check and or on a conceptual note still.

Availability check can be configured both at requiremnt class and at the schedule line categories level.

Whilst the availabilty check at the requirement class level via global and mandatory configuration the schedule line catgry availability check deals with the order.

It is mandatory that the reqmnt class is flagged off for avlblty check and the schdelu line cat need not be.

The following are the mandatory for Availability check to happen--

1. Must be swithced on at the requirment class level and at the schedule line level.

2. Reqmnt type must exist by which a requiremnt class can be found

3. There must exist a plant and is defined

4.Checking group must be defined in Material Master records(it controls whthr the system is to create individual or collective reqmnt)

A combination of checking gropup and checking rule will determine the scope of availbaility check.