I feel we need some clarity here - the document type is configurable, and therefore "AB" may not be the same at every site. Also, what are you wanting the FI document you are posting to actually do - just a simple DR & CR to GL accounts, or an intercompany journal, or a mixed vendor / customer clearing? Typically the choice of transaction, not document type per se, will be more important... plus your site may have non-system business rules that drives the document type you should select e.g. "YA" might be used for customer refunds at Site 1, and "YA" might be used for an interface journal at Site 2 ... check with the functional / business team.
Jonathan
