Posting keys are used either to debit the account or credit account. With definition of posting keys we can also control field status of accounts. Sap has already defined the posting keys we can use those as it is. Otherwise if the client specifically requests you to create defined postings we can define them as per the request. The following are the important posting keys.
I suggest you to verify the attributes and convince the client to use the default posting keys. The screen of the posting keys will appear as under. If you want to know the attributes select any posting key and click on details button or double click on the posting key.
Path: spro>img>financial accounting>financial accounting global settings>document>control> line items>define posting key: TC OB41
