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| Defined in: XPath 1.0 |
| Parameters: object obj (required) |
| Return type: node-set |
Normally, this function is used to return the single node with an ID that matches the string value passed in as a parameter. When a space-separated list or a node-set is passed in, it will return the union of all nodes that individually match the IDs. This function normally appears on the left-hand side of a path expression.
The XPath 1.0 Recommendation states that "If a document does not have a DTD, then no element in the document will have a unique ID." In XForms, a DTD will never be associated with instance data. An XML Schema, however, has a datatype called xs:ID, which can be associated with an instance data node to provide an indication that the node contains a unique id. Thus, it is still possible for the id( ) function to be useful in XForms, though it takes a little extra work.
This example selects the element with the unique ID "taxtable" (if any) and returns a node-set of all the rate element children:
id("taxtable")/rate