In a message definition, the segment grammar determines the segments of the message to be parsed and the order in which they appear.

To set up the segment grammar:

• In the Workspace, locate the message definition that you just created, and double-click Message Grammar. The Message Grammar window appears:

Message Grammar Window, Showing Segment Grammar Panel Highlighted

The Segment Grammar panel of the Message Grammar window already contains the MSH segment. This was added by the Create Message Definition Wizard, since every HL7 message contains an MSH segment. Because the channel you are creating in this tutorial will be processing patient demographic information, you need to add the PID segment to the segment grammar.

To add the PID segment to the segment grammar:

• In the Workspace, in the Segments section, locate the PID (Patient Identification) segment.
• Drag this segment from the Workspace and drop it into the Segment Grammar panel.

Adding the PID Segment to the Segment Grammar Panel

Notice that the Ignore Segments not in Grammar option is checked. This ensures that Chameleon will ignore any other segments it encounters for this message. This makes configuration much faster and ensures that the configuration will not be broken if new segments are added to the incoming messages.

Now that you have created the segment grammar, the next step is to define a table that will contain the information that you extract from the messages matched by your message definition.