Like messages, segments can also have Identities. This is very useful for certain kinds of segments like OBX segments. Due to the nature of OBX segments, they will often have very different kinds of data in them depending on what kind of lab result data they represent.

The main advantage for using Segment Identifiers is that if a segment matches not just the segment identifier, but also a regular expression to match one or more fields within the segment, you can easily distinguish between two different types of the same segment. For example, if a segment has an identity the segment matching algorithm looks at two things:

• The three-letter identifier (e.g. OBX, PID, etc.) at the start of the segment; and
• The matching rules defined in the Segment Identity window.

The matching rule allows you to match one or more fields with a regular expression.

For more information, see Defining the Segment Identity.