HL7 Variant quirk….

Maybe I’ve just never encountered this before or never realized that syntax is everything but here is an issue I just ran into.   I have a variant built with an AL1, ZAL repeating group.  I needed to do some translations on the AL1.3 field based on allergy type in AL1.2.  Simple enough.  However, in some of my test messages only the first AL1 segment was showing up.  It would never hit the others.  I searched long and hard in my code making sure I had all of my iterate variables in place and made sure I had no typos.  Everything looked good.

Then I noticed that the A08’s were working fine but the A04’s and A31’s weren’t.  The layout up to those segments are pretty much the same in this variant for all 3 messages.  So, if I use an A08 as my message format for my xlate, I was safe to assume that it should be working properly.  However, finally I went to take a look at the structure defined in the variant for each type of message.  Here is what I found:

The A08 group was set up as below with the corresponding layout in the xlate:

[                     Layout in xlate:  1(0).0(0)….

{                                            1(0).0(1)…and so on

  AL1

  [ZAL]

 }

]

The A04 group was set up as below with the corresponding layout in the xlate:

{                     Layout in xlate:  1(0).0(0)….

 [                                            1(1).0(0)…and so on

  AL1

  [ZAL]

 ]

}

Can someone explain to me why whether the curly brace or the bracket came first made such a difference in the way the xlate translated the message?

Thanks…

Tom Rioux

Baylor Health Care System