The <descriptorSwitch> element contains a set of alternative descriptors to be associated with an object. The choice is made during presentation time.
Test rules used to choose the <descriptor> element are defined by <rule> and <compositeRule> elements; <bindRule> child elements associate these rules to child <descriptor> elements of the <descriptorSwitch> element.
The rules are evaluated in the order they are defined. The first rule evaluated as true determines the chosen <descriptor> element. If all rules are evaluated as false, a default <descriptor> element, defined by the <defaultDescriptor> element,is chosen; if the <defaultDescriptor> element is not defined no descriptor is selected and the NCL player behaves as if the element does not exist.
| Element | Attributes | Content | Parent |
|---|---|---|---|
| <descriptorSwitch> | id | (<defaultDescriptor>?, (<bindRule> | <descriptor>)*) | <descriptorBase> |
| Name | Value | Description |
|---|---|---|
| id | It may receive any string value that begins with a letter or an underscore and that only contains letters, digits, “.”, and “_”. | The id attribute uniquely identifies the element within a document. |