A section of cable between components or devices. A segment may consist of a single patch cable, several patch cables that are connected, or a combination of building cable and patch cables that are connected.
In Internet communications, the unit of transfer between TCP functions in different machines. Each segment contains control and data fields; the current byte-stream position and actual data bytes are identified along with a checksum to validate received data.
Example of usage – “In IMS/VS, the unit of access to a database; for the database system, the term segment refers to the smallest amount of data that can be transferred by one DL/I operation. For input terminal operations using the DC feature, a segment is defined by the particular terminal type and is obtained by the application program with one call.”