When Standard Purchase Codes are being created they can be used with General Ledger Account Codes and will default in Posting Groups (VAT Prod. Posting Group and Gen. Prod. Posting Group) from the G/L Account. You can specify Dimensions and Amounts Excl. VAT but there is no way to override the Posting Groups that default from the G/L Account. There are situations where for specific frequent purchases you might want to change the setup so it doesn't have to be changed manually every time.

For instance, you may have different types of subscriptions, some of which may be vatable and some which may not, rather than setting up two separate GL Accounts with different defaults or manually changing on every document it would be nice to be able to setup a Standard Purchase Code with a different VAT Prod. Posting Group.