Segments
A segment is a logical unit of information, like a data record.
The Segment type is partitioned by initiator values. Each segment begins with a unique 2 or 3 character initiator, which identifies the segment. For example, the ACT segment begins with the initiator ACT.
Because an Element Delimiter must follow the segment initiator value and precede the first data element, each segment is defined as prefix delimited by the Element Delimiter and has a terminator of Terminator Delimiter.
Components of a segment might be Element types, MComposite types, and XComposite types. The segments are defined to comply with the rules specified in the X12 documentation.