OrderQty(38) usage in NewOrder-Single for Convertible Bonds

Imported from previous forum

In a NewOrder-Single message for a convertible bonds, is the OrderQty(38) field always expressed as a “notional” amount or it can also be expressed in units? If both ways are possible, is there another field that should specify how the qty is expressed? For example, the field ContractMultiplier has to be specified when the qty is expressed as “notional” ?