definiens: means, for any Agreement Year ( or any Agreement Quarter or six - month or nine -month period prior to the end of an Agreement Year ), the Total Net Sales of t he Product in the Territory for the applicable period from prescriptions writte n by all physicians of all specialties and practices, divided by the total num ber of retail ( TRX ) and mail order prescriptions ( TRX ) for the Product that are written or ordered in such applicable period by Covered and Non - Covered Physic ians . The number of retail ( TRX ) prescriptions shall be determined by the Nati onal Prescriptions Audit Plus : Prescriber Specialty Report as issued by IMS America . The number of mail order prescriptions shall be determined by [COMPANY] usin g internal data in accordance with its historical customary practices ( with the A verage Selling Price for mail order prescriptions to be adjusted ( i.e., trued up ) to be equivalent with the number of tablets per prescription on a retail basi s )