Before your application can generate HL7 messages, you must determine the format of the messages that you will be generating.

Some good practices to follow are:

• If the message recipient expects the message in a particular format, you should obtain an interface document from the recipient. This document should specify the type and format of the messages the recipient will accept.
• If possible, obtain an actual data sample from the message recipient. This sample should contain messages that the recipient will accept as valid and properly formatted. The sample messages can be used to design the HL7 interface.

An interface document and some sample messages will give you the information you need to design a well-formed interface.