Which of the following best describes HL7's messaging structure?

• A. File-based batch transfers
• B. Segment headers and delimiters-based messages
• C. Email-like plain text messages
• D. API-based RESTful messages

Answer: (B)

HL7 v2.x messages are built as a sequence of segments, and each line begins with a 3-character segment identifier (like MSH, PID, OBX) that tells you what kind of data follows in that line. Inside each segment, data fields are separated by a delimiter defined in the header segment (typically a pipe character), with components and subcomponents separated by other delimiters (for example, ^ for components). The header segment itself defines these delimiters, so the whole message is parsed consistently from the segment headers and the delimiter rules. This delimited, segment-driven structure distinguishes HL7 messaging from file-based formats, email-style plain text, or API-based RESTful messages (the latter being characteristic of newer standards like FHIR).