XML Schema 参考手册 完整 XML Schema 参考手册 The selector element specifies the XML path language (XPath) expression, which selects a set of elements (unique, key, and keyref elements) for the identity constraint. 父元素: Key, keyref, unique (? The symbol declares that the element can appear zero or once in the restriction element. ) Attribute Description Id Optional. Specifies the unique ID of the element. Xpath Necessary. Specifies the XPath expression relative to the declared element. This expression identifies the child elements to which the identity constraint (the declared element) is applied. Any attributes Optional. Specifies any other attributes with the non-schema namespace.Definition and usage ¶
Element information ¶
Grammar ¶
<selector
id=ID
xpath=a subset of XPath expression
*any attributes*
>
(annotation?)
</selector>