Page "RS-232" Paragraph 37

RS-232 devices may be classified as Data Terminal Equipment ( DTE ) or Data Communication Equipment ( DCE ); this defines at each device which wires will be sending and receiving each signal.

The standard recommended but did not make mandatory the D-subminiature 25 pin connector.

In general and according to the standard, terminals and computers have male connectors with DTE pin functions, and modems have female connectors with DCE pin functions.

Other devices may have any combination of connector gender and pin definitions.