Defines 37-pin and 9-pin connectors and the assignment of connector pin numbers of the interface between data terminal equipment and data circuit-terminating equipment where CCITT Recommendations V.24 with V.10 and V.11 apply. References: ISO 2110, 4903, CCITT Recommendations V.10, V.11, V.21, V.23, V.24, V.26, V.26 bis, V.27, V27 bis, V.27 ter, V.28, V.29, V.36.