iNTERFACEWARE™ Inc.

Z-Segments

While developing the standard, the HL7 committee realized it was impossible to standardize all the aspects of data exchange in the healthcare industry. This is why they provided a framework for the addition of custom information into HL7 messages, more commonly referred to as Z-segments. You may define a custom segment and include it in any HL7 message. These segments should be named starting with letter Z, (e.g. ZPD for custom patient demographics information). Applications that do not know the meaning of your Z-segments should simply ignore these segments.

The downside of the Z-segment approach is that you cannot expect any particular piece of information to be in a specific place. While one vendor will send this information in some segment of the standard, another will send it in a custom Z-segment.

When selecting a toolkit to deal with HL7 integration, it is extremely important that your code be shielded from the actual message structure.

When you refer to a field such as PID.ExternalId in your code, you will have to change your code if this piece of information begins to appear instead in a ZPD segment.