S IBXDATA=$S($$COBN^IBCEF(IBXIEN)=1:"",+$$MRASEC^IBCEF4(IBXIEN):"M",1:"N")
FORMAT CODE DESCRIPTION
If the bill payer is secondary to MEDICARE WNR with an MRA on file
output 'M'. For non-secondaries, output nothing.
For non-MRA secondaries, output 'N'.