Multiple Configurations are very useful in interface design because it reduces the maintenance effort and cost for supporting various flavors of HL7. Essentially this means that as long as the interface in your application is consistent (i.e. tables and table grammars that comprise your VMD), everything else can change (i.e. segment grammar, message identity, table mappings, segment and table Python scripts, etc.), as shown in the following diagram:

	Important Notes In the above diagram, the dark blue boxes denote which components can change within each configuration, while the light blue boxes indicate which components must remain constant. Each VMD file can contain an unlimited number of configurations. The message definition matching order can be different between each configuration in your VMD file.

There are many situations in which you might want to utilize multiple configurations. For example, you might want to re-use the same VMD file and deploy your application at multiple sites. As long as you're processing the same type of message, you can just add another configuration instead of re-creating tables and table grammar. The only thing you would need to do is set the configuration in your code or VMD file before deploying it.

In the following section a problem scenario will be presented to you, along with its solution.