When setting up an HL7 interface, the most fundamental question that you need to ask yourself as a developer is how much information do I require? In most cases, you will need either:

• Only a small subset of the information, or
• Just about everything.

If you only need a small subset of the data then you are very lucky - you'll be able to save yourself a lot of work. On the other hand, if you know you need just about everything then you can definitely minimize your work by designing your segment grammar accordingly.

Your segment grammar design must be driven by your data requirements.