This standard is applicable to the interconnection of data terminal equipment (DTE) and data communication equipment (DCE) employing serial binary data interchange. It defines: Section 2 ?C Electrical Signal characteristics:- Electrical characteristics of the interchange signals and associated circuitry. Section 3 ?C Interface Mechanical Characteristics:- Definition of the mechanical characteristics of the interface between the data terminal equipment and data communication equipment. Section 4 ?C Functional Description of Interchange Circuits:- Functional description of a set of data@ timing and control interchange circuits for use at a digital interface between data terminal equipment and data communication equipment. Section 5- Standard Interface for Selected Communication System configurations:- Standard subsets of specific interchange circuits are defined for a specific group of data communication system applications. In addition@ the standard includes: Section 6- Recommendations and Explanatory Notes Section 7- Glossary of New Terms. This standard includes thirteen specific interface configurations intended to meet the needs of fifteen defined system applications. These configurations are identified by type@ using alphabetic characters A through M. In addition@ type Z has been reserved for applications not covered by types A through M@ and where the configuration of interchange circuits is to specified@ in each case@ by the supplier. This standard is applicable for use at data signaling rates in the range from zero to a nominal upper limit of 20@000 bits per second. This standard is applicable for the interchange of data@ timing and control signals when use din conjunction with electronic equipment@ each of which has a single common return (signal ground)@ that can be interconnected at the interface point. It does not apply where electrical isolation between equipment of opposite sides of the interface points is required.