Furthermore, Schema enables you to specify the scope within which uniqueness applies whereas the scope of an ID is fixed to be the whole document. These characteristics of attribute groups make them similar to parameter entities in XML 1.0. Note that an attribute group may contain other attribute groups. The complex types in the instance document, and some of the simple types, are defined in the schema for purchase orders. Its value must be 37. (2, unbounded) 37, — n/a Element must appear twice or more. However, attribute declarations do not need to be repeated in the derived type definition; in this example, RestrictedPurchaseOrderType will inherit the orderDate attribute declaration from PurchaseOrderType. The easy to use Wizard driven interface also generates HTML documentation for your custom API along with a Sample Application.
Elements that contain subelements or carry attributes are said to have complex types, whereas elements that contain numbers (and strings, and dates, etc.) but do not contain any subelements are said to have simple types. Constraint comparison is in terms of their value rather than lexical strings. ❮ Previous Next ❯ What is a Simple Element? A simple element is an XML element that can contain only text. It cannot contain any other elements or attributes. One caveat is that global declarations cannot contain references; global declarations must identify simple and complex types directly.
Refer to the aldeed:collection2 package documentation for examples. Secondary uses for XML Schemas The primary reason for defining an XML schema is to formally describe an XML document; however the resulting schema has a number of other uses that go beyond simple validation. The report might contain another code attribute, but its value does not have to be unique because it lies outside the scope defined by the XPath expressions.