A designation for a particular type of connector.

DB-9M Function Abbreviation\\
Pin #1 Data Carrier Detect CD\\
Pin #2 Receive Data RD or RX or RXD\\
Pin #3 Transmitted Data TD or TX or TXD\\
Pin #4 Data Terminal Ready DTR\\
Pin #5 Signal Ground GND\\
Pin #6 Data Set Ready DSR\\
Pin #7 Request To Send RTS\\
Pin #8 Clear To Send CTS\\
Pin #9 Ring Indicator RI\\
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