Top view is the IDC portion of the connector
Insulation Displacement Connector. [IDC] A connector that cuts through the insulation of a conductor to make contact with the wire, also called an Insulation Displacement Connector. A two-part connector for Flat Cable systems. Nominal spacing; 2.54mm.
Cables may be round, twisted or flat, but they must be flat as they are terminated by the connector. Normally cables are flat ribbon cables that terminate at the connector, but some cables are twisted pairs or flat cables twisted into a round cable. In any case the cable needs to be flat as it enters the connector for termination. However the cable may contain discrete wires, not formed as a ribbon cable. Another example view of an IDC Connector, the drawing is from MIL-A-A-55140 [IDC on one side, bail locking on the other end].
Insulation Displacement Connectors come in many different forms, most mount to a Printed Wiring Board [PWB]. But some do mount to another cable connector, as shown above. A D Sub-Miniature [D-Sub] connector is one of many connector styles that may contain a IDC terminating connector.
The DOD Specification Sheet MIL-DTL-24308/27 describes a IDC connector in a D-sub format.
MIL-DTL-24308/27: Connectors, Electric, Rectangular, Miniature, Polarized Shell, Rack and Panel, Insulation Displacement, Socket Contacts, Non-environmental.
IDC Subminiature D Connector Shell Dimensions
The also make IDC connectors to DIP sockets MIL-DTL-83503;
MIL-DTL-83503/6 Nonenvironmental Electrical 0.050 Centered Flat Cable Connector Dual In-Line Plug for Mating to Standard DIP Sockets; .100 X .300, .100 X .400, and .100 X .600 contact spacing. This standard allows DIP packages with 8, 14, 16, 18, 22, 24, 28, or 40 pin contacts. That is, a an IDC termination on one end and male pins on the other end that conform to normal IC pin spacing. Allowing an IDC connector to use a normal IC layout pattern on a printed circuit board.
An IDC connector needs to have blades on one side of the connector to pierce the insulation of the cable, but the reverse side of the connector could interface to almost any style of connector. The most common interfaces for an IDC connector include either an open pin header or a shrouded header. However D-sub connectors are also commonly used with IDC connectors, even BNC connector might use and IDC connection.