This European Standard specifies methods for measuring the end-to-end transit time of the domestic and cross-border priority single piece letter mail, collected, processed and distributed by postal service operators. It considers methods using a representative end-to-end sample of all types of single piece addressed letter mail. End-to-end is defined as from the point mail is placed into the collection/acceptance system under the responsibility of the postal operators, to the final delivery point under the responsibility of the postal operators. The overall transit time quality-of-service result is to be expressed as percentage of mail delivered within J + n days end-to-end according to the EC postal directive. This quality of service indicator does not measure the postal operator’s overall performance in a way that provides direct comparison of postal service operators, and does not include other service performance indicators than those related to transit time. In particular this European Standard does not measure whether the timing of the last collection of the day meets customer’s requirements. It specifies a set of requirements for the design of a quality of service measuring system for single piece priority mail, involving the selection and distribution of test item sent and received by selected panellists. The sample design gives the specifications for the item to be representative of the real mail flows. This European Standard relates to the measurement of the so-called “normal” services given to private persons / households and businesses that post mail at street letter boxes, over the counter at post offices, have pick ups at their offices or give their mail directly at postal service operators sorting centres. For technical reasons this European Standard may not in all parts be suitable for the measuring of very small volumes of mail and for operators with limited coverage.