The beating heart of the CORE HL7 Message Matching Engine is the Matching Instruction.
A Search / Filter Script is just a collection of Matching Instructions and in this topic we will discuss how to create a SINGLE matching instruction. See Searching For HL7 Messages for how to create Search / Filter scripts that can each contain multiple matching instructions (called Field Instructions when part of a script) for compound queries.
You edit (or create) Matching Instructions in the Edit a Matching Instruction window which you get to either by entering a Quick Filter in the Main Window., or by Adding or Editing a Field Instruction in the HL7 Search / Filter Matching Instructions window. You can also access Matching Instructions when you Import HL7 Messages From A Folder.
Simple Matching Instruction
If you examine the screenshot above you can see what this simple matching instruction is doing:
•For the PID (Patient Identification) Segment.
•Field #5, Component #1, SubComponent #1 (The Patient Last Name).
•Only Match if that field Value Begins With A or S or G (not Case-Sensitive).
Let's look at another example.
A more complex instruction
When you examine this screenshot something a bit different is happening.
•For the PID (Patient Identification) Segment.
•Field #9, Component #1, SubComponent #1 (The Patient Alias).
•Only Match if that field Value is Equal To Smith or Jones or Bartlett (not Case-Sensitive).
•AND we have also indicated that if the field repeats it can be true for Any Instance.
Field #9, the Patient Alias contains a person's NAME (just like the Patient Name) but it can be a repeating field, people can have multiple aliases. Our instruction says to look at ALL repeating instances of this field and if ANY of them are Equal To Smith or Jones or Bartlett (not Case-Sensitive) this will MATCH.
First, we looked at a simple matching instruction, then we looked at a more complex example. Let's look at a REALLY SIMPLE example that only uses the Primary Condition.
A VERY Simple Instruction
When you examine this really simple instruction we don't have much of anything It says.
•In the HL7 message there must be an OBX Segment.
That's it. By checking the That is the only condition box under the Must Exist In the Message box we are telling the Matching Engine that for a message to match it MUST contain an OBX segment. Likewise we could have checked Must NOT Exist in the Message and the reverse would be true, any HL7 message that CONTAINS an OBX segment would NOT match.
See Searching For Messages for instructions on how to create a script that contains multiple matching instructions chained together to form complex queries.
