For each customer (vendor), one card is usually defined within the system. Each customer/vendor card can be linked with a customer/vendor posting group which means with one receivables (payables) G/L account. It is a frequent case that receivables (payables) amounts of a customer (vendor) should be posted to different G/L accounts, depending on a business transaction type. e.g payables (receivables) due to current operations and paid deposits. It should be possible, to have such possibility and be able to change customer/vendor posting group per transaction.

Functionality allowing to use different customer/vendor posting groups when posting to one customer/vendor card was part of so called "EAST" regional layer for Eastern European countries for NAV versions 5.0 SP1 FP1 and 2009 (and in some cases later ones). A lot of Eastern Europe localizations still have such or similar functionality as it's deemed to be critically required by customers.

This worked that way that that is assigned to the customer (vendor) card was actually a default posting group and where copied to all documents. However, the user could change the group while entering a document, without changing a default customer (vendor) posting group in a relevant card. Possibility to change posting group was limited to list of possible "substitutes" of default posting groups, so it was easy to control, that change was done within allowed boundaries.