BizTalk 2002 Map against ASCX12 837 do***ent functoid? I need an E

I have a Hierarchal level in the billing provider on an inbound ASCX12 
do***ent that can have multiple REF statements. My map only looks at the 
first REF Statement. I figure I need a special functoid. I saw something
from 
another website about using an enum in my functiod script. Is that
possible? 
Does anyone have an example of one?

Here is what my current code looks like in the functoid:
' inbound do***ent is HIPAA ASCX12 837 professional service
' the billing provider secondary identification area may contain several 
iterations of the REF segment
Function FctRenderingProviderOPSvcs(ByVal p_strParm0, ByVal p_strParm1)
    ' Check for Billing provider in 2010AA
    If p_strParm0 = "LU" And p_strParm1 <> "" Then
        FctRenderingProviderOPSvcs = mid(p_strParm1, 1, 5)
    Else
        FctRenderingProviderOPSvcs = "99999"
    End If
End Function


Here is what the data looks like:
ISA*00*          *00*          *ZZ*RSN            *ZZ*400            
*070112*1108*U*00401*000000497*0*P*:
GS*HC*413*400*20070112*1108*497*X*004010X098A1
ST*837*0001
BHT*0019*00*200701123987*20070112*110819*RP
REF*87*004010X098A1
NM1*41*2*GC*****46*413
PER*IC*GEORGE J ST JOHN*TE*5097358681
NM1*40*2*MHD*****46*400
HL*1**20*1
NM1*85*2*MY HOUSE*****XX*1234567893
N3*105 WEST MAIN STREET
N4*CLARKSBURG*WA*98620
REF*EI*91-1043304                        <--
REF*1J*038                                    <--
PER*IC*sALLY MAE*TE*999999999
HL*2*1*22*0
SBR*P*18*A31709*413*****ZZ
NM1*IL*1*FLINTSTONE*FRED****MI*PICCODE1A
N3*202 QUARRY WAY
N4*BEDROCK*WA*98000
DMG*D8*19550709*F