Use of derived types

XML Schema provides a mechanism to define a new type that is derived from an existing type. The new type can be either an extension, or a restriction, of the existing type. This construct is used in the ISF Core schemas to reflect business components that are based on other business components.

In an XML instance document (such as a Transaction Document) it is permitted to override the type of individual elements (using the xsi:type attribute) to choose another type that is derived from the type that is defined for the element.

This practice is common in Transaction Documents to override the type of Party elements to choose one of the extensions for Party, for example, Person, Organization, FinancialInstitution, or to choose an extension for a party role element, for example, DebtorRole, DebtorAgentRole. For an example, see Sample ISF document.

Additional types can be defined, as part of an ISF extension, that are derived from ISF Core business component types. These derived types can then be used to override the type of existing ISF elements within a Transaction Document.