Probably won't want to look at the HL7 message data content. More likely the client will want to answer questions like:

How many ADT A01's went to system XYZ.


Provide a summary of message types and counts sent from system ABC

That type of thing. In order to do that, if there is some documentation that helps them navigate the data model, that would help them.

I have SQL for these types of queries, but the client wants to do it themselves and wants to be able to understand the data model.