Initially defaults a pay category as follows:
If you have set up a standard or user pay category override in F3 Properties (not recommended), defaults the F3 pay category.
If no F3 override exists, defaults the pay category specified for the current user in VA User Profile.
If no override pay category is specified for the user, defaults the pay category defined in AP Company Parameters.
If no default pay category is defined for the company, default will be null. (In this case, the pay type will default from AP Company Parameters based on the line's type.)