Hello Karan
You already have very solid information received from other experts.
From my notes, I have following stepwise process to share with you. It describes all the steps "How To" part and "Why" you need particular configuration. Please see.
1. Field Catalog : With this activity, you can add new fields that you use for creating the condition tables. (/SAPCND/AO01)
2. Condition Table : In this activity, you create the condition tables used in the rule-based ATP check.(/SAPCND/AO03)
3. Access Sequence : In this activity, you determine the access sequences. Using the access sequence, you determine: Which condition tables are used to access the condition records. The sequence of these condition tables Which field contents are used as criteria for reading the condition tables. (/SAPCND/AO07)
4. Condition Type : In this step, you maintain the condition type and assign it to an access sequence. Condition types are used for determining rules in the rules-based availability check. (/SAPCND/AO06)
5. Maintain Rule Strategy : In this step, you maintain the rule strategy. The rule strategy determines the condition types and defines the sequence in which they are evaluated.
6. Assign Rule Strategy : In this activity, you determine the following activation parameters to determine the rule strategy:
----> Technical scenario
----> Business transaction (need to define using Tcode. V0V8 in ECC)
----> Action type
7. Maintaining the Rules (/SAPAPO/RBA04):
----> Creating Product Substitution Rules : In this activity, you create the substitution chains for product substitution.
----> Defining the Rules Control : Using the rule control you can define the strategy. For example, the rule control determines whether the system checks the same product in different locations, or it checks a substitution product, first.
----> Defining the Location Determination Procedure : For the location determination procedure, you define a list of locations. During the availability check, SAP APO takes all listed locations into account. If the requirement cannot be fulfilled in the original location, it is substituted by one of the alternative locations.
----> Maintaining Rules : The rule combines the possibility of location and product substitution with the rule control strategy.
8. Creating the Rule Determination(/SAPCND/AO01) : In the rule determination, you enter data for the key combination of a condition table and assign a rule to it.
9. Last but not least, The prerequisite to trigger Rules Based ATP Check is "Activate RBA" checked in the Check Instruction. Besides there are few additional(optional) check boxes which offers some additional functionality namely Start Immediately, Use Calculation Profile etc.
Hope this will help.
Thank you
Satish Waghmare