# XV-MY-18

Source: https://xmlvalid.com/rules/XV-MY-18

> The SST registration number of the supplier and of the buyer is a mandatory field: cac:PartyIdentification/cbc:ID with schemeID SST, NA when not registered; the … has none.

- Level: warning
- Rule sets: MyInvois validations of LHDN (Malaysia) MyInvois SDK of 25 September 2026
- Context: `/*/cac:AccountingSupplierParty/cac:Party | /*/cac:AccountingCustomerParty/cac:Party`
- Test: `exists($sst)`

Validate a document against these rules: https://xmlvalid.com/validate