Hi Robin,
External transaction code NMSC and NTRF both are assigned to posting rule Z010 in OT83.
In your case,two search strings have been configured on the basis of posting rule to post note to payee lines "Monthly Charges" and "Thard Party Charges" to posting rule Z010 which is aligned to GL account hrough account symbol in OT83.
Please check OTPM, in search string field you will find text "Monthly charges" and "Third Party Charges" with target field Z010 (Check in mapping area).
check "Search String Use" in OTPM, here both the search string have been defined with respective external transaction type NMSC with "Monthly Charges" and NTRF with "Third Party charges" with target field posting rule.
During upload EBS file, if system will find "Monthly Charges" with code NMSC and "Third Party Charges" with code NTRF then will post to GL account which is linked to posting rule Z010.
Hope it is clear !
Regards,
Mohammed Kalim