In this step, you will use Chameleon to set up a VMD file. This file performs tasks such as mapping data, data transformation, and converting data to and from XML.

This VMD file will contain the following components:

• A message definition, which represents an HL7 message type (such as "Register a Patient"). You can have more than one message definition in a VMD file.
• A message identity, contained in the message definition, which provides what fields are to be used as the message type, and what these fields need to contain.
• A segment grammar, which indicates what message segments are expected, the order in which they appear, and whether they repeat.

The following sections describe how to create these components and how to set the XML translation scheme that this VMD file will use.