New at DTL. I need some pointers on this DTL

For all Prosthetics orders:
when ORC-1(Order Control) is "NW" (New Order), need to update OBR-18(Placer Field 1) based on PV1-2 (Patient Class) value.
assumption is that the selection logic is that all prosthetics orders with OBR-18 field is always blank.
Description :
If PV1-2 is I, insert I in OBR-18
If PV1-2 is O, insert O in OBR-18
If PV1-2 is E, insert O in OBR-18
If PV1-2 is P, insert O in OBR-18
If PV1-2 is R, insert O in OBR-18
If PV1-2 is B, insert O in OBR-18

I added extra OBX segments and I need to renumber OBX 4 so they are sequential.

Business Process is adding control characters.

Input HL7 shows no control characters in Notepad ++

Output

Code:

Method FromCerner(pRequest As EnsLib.HL7.Message) As %Status
{
    #dim tStatus As %Status = $$$OK
    #dim eException As %Exception.AbstractException
    #dim tOBXText As %String
    #dim tItemNumberCount As %Integer = 0
    #dim tItemNumberProcessed As %Integer = 0
    #dim tTotalCostSegment As %Integer = 0
    #dim tOrderType As %String
    #dim i As %Interger = 0
    #dim tOBXKey As %Integer = 0
    #dim tOBXTextChanged As %String
       ////
       Set pOutput = pRequest.