Pass variable to Iteration

I have an OBX iteration that I need to pass in a variable on the nth iteration within an IF statement.

(assuming that all other variables have been declared):

I have a variable that keeps the value of %g2 and some other code that checks other fields for a string match.  When a match occurs, I need the value of %g2 because I will use it to change a particular OBX field (in my cause OBX14) on “that” iteration.

Is it possible to pass in a variable in an iteration and how? I’ve tried the line below but it didn’t seem to help.

1(0).1(0).1(@lastOBX).OBX(0).00573(0).[0].[0]

FOR TESTING, I can hard code the value of @lastOBX and the field within the message will change.

1(0).1(0).1(HardCodedValueHere).OBX(0).00573(0).[0].[0]

Summary –

What am I trying to accomplish?

Answer:   Change OBX14 on the very last iteration

Thanks for any help,

Austin