Suppose that you need to design an application, to be written in C# .NET, that generates HL7 messages of type ORU^R01, also known as "Unsolicited Observation Result" messages. In messages of this type, ORU indicates that the message is a laboratory result of some kind, and R01 denotes an observation result. An Unsolicited Observation Result contains all the information specified for a lab result announcement.

When a lab report is issued, your application must create an ORU^R01 message and populate it with the following information:

• Patient id
• First name
• Surname
• Date of birth
• Social Security number

In addition, the application must encode the laboratory results into the message, and must provide all other information required by the HL7 standard, including the time when the message was generated.

The initial sections of this tutorial assume that your application contains internal data structures that hold the data to be encoded in an HL7 message. Your task will be to transform this data into the HL7 standard format. Later on, in Step 4 - A Sample Client Application, you will learn how your application can acquire data.

	The choice of C# .NET is purely arbitrary and does not materially affect any of the design choices that are discussed in this tutorial.