Now that you have specified the segments that your VMD file will process, the next step is to create a message definition. This message definition will be used to recognize and transform incoming messages.

To create a message definition:

• From the Chameleon toolbar, click Browse. The Message Browser appears.
• Paste the sample ADT message into the Message Browser.
• Click Parse. The Message Browser will notify you that it does not recognize the message:

Unrecognized Message

• To fix this, right-click the top panel of the Message Browser and select Create Message Wizard. The Create Message Definition Wizard appears:

Using the Create Message Definition Wizard

• In the Name field, replace PersonUpdate with Default.
• In the Description field, type Person Update.
• Click Finish to create the message definition.

The new message definition now appears in the Message Definitions folder of the Workspace:

This message definition consists of three components: a message grammar, a message identity and a transformation script. You will be creating the transformation script later in this tutorial.

The message grammar is required when fields in message segments are mapped into fields of data tables. Since this VMD file is to be used for transformation only, you do not need a message grammar.

The message identity is created by the Create Message Definition Wizard. Chameleon uses this message identity to determine which incoming messages are to be processed by this message definition:

This message identity specifies that messages will be matched if:

• The Message Code subfield is ADT (Message Code is MSH.9.1, which is the first subfield of the ninth field of the MSH segment);
• The Trigger Event subfield is A31 (Trigger Event is MSH.9.2, which is the second subfield of MSH).

	The Message Code and Trigger Event subfields are the fields that are normally used to identify the type of an HL7 message.