This part of 61076 relates to the plug-in sockets designed for in-line electronic packages of assessed quality. Sockets covered by this specification are devices which provide a means of interchangeability between devices and compliance between mating limits. The scope of this specification covers sockets for packages with contacts having one of the following in-line formats. a) Single in-line sockets. b) Dual in-line sockets. c) Quad in-line sockets. d) Zig-zag in-line (staggered) sockets. The object of this specification is to define: - a unified numbering system; - functional levels and standard test methods and gauges for use in the examination of these sockets; - appropriate reference dimensions of the mating device and board layout to establish intermateability and interchangeability criteria. Test severity and performance require-ments prescribed in detail specifications referring to this sectional specification shall be equal to, or greater than, those specified herein; degradations are not permitted.