What is the atomic unit of data transferred between systems in healthcare called?

In the context of HL7 standards and healthcare data exchange, the atomic unit of data transferred between systems is referred to as a "Message." A message serves as a complete unit that encapsulates all the relevant information needed for a particular healthcare transaction or communication, such as patient admission, laboratory results, or billing information.

Each message contains structured content that conveys clinical and administrative data in a format that can be reliably interpreted by different systems. This encompasses various components, including segments, which are groups of related data fields, but the overarching unit that represents the entire communication is the message itself.

In comparison, a field refers to a single piece of data, while an element is often used to indicate a part of a field. A segment comprises multiple fields that together describe a specific part of the message. Understanding the structure of HL7 messages is crucial for effective data exchange and interoperability between healthcare systems.