What architectural feature defined HL7 version 2 messages requiring complex parsing?

Pipe-and-caret delimited messages

The Health Level Seven version 2 (HL7 v2) standard, which was instrumental for decades in facilitating crucial communications such as the exchange of lab results and handling admissions, relied on a specific message structure. This structure used pipe-and-caret delimiters to separate data segments and fields within the transmitted messages. Although this format allowed for essential data exchange between disparate systems, interpreting these messages necessitated the use of complex, often brittle, parsing rules. Consequently, the reliability of data exchange using HL7 v2 was heavily dependent on specialized software components known as interface engines, which were necessary to translate these delimited messages into formats that specific applications could actually understand and utilize.