SAP Authorization in Role Using $AUART variable

Experts,

I Need to Authorize User a certain types ou Order,

Creating a Single Role to all user segregating values by variables.

I am using the  V_VBAK_AAT Object. restricting field AUART by Variable $AUART

Do you know the next step to fill $AUART values?

Is pn an exit?

Is on a transaction?

Can anybody guide me to next steps?

Best Regards