Enabled only when the 'Using Payable Category' option is checked.

Specify the pay category to use as a default when entering transactions in AP and PO Purchase Order Entry (if PO Company flag set to do so). This pay category is used in conjunction with the transaction's line type to determine the default pay type.

If you have defined a default pay category at the F3 Properties level (not recommended) or in VA User Profile, it will override the default pay category specified here. If no override defaults are specified and this field is null, transaction pay types default from the 'AP Company Payable Types', depending on line type.