Composite nodes of NCL, represented by <body>, <context>, and <switch> elements, encapsulates their child components. Interfaces of child components are not visible to relationships defined outside of the composite node, unless these interfaces are externalized, using the <port> or <switchPort> elements.
The <port> element specifies a composite node port with its respective mapping to an interface (interface attribute) of one of its components (specified by the component attribute). As usual, if the interface attribute is not specified, the whole content anchor is assumed.
| 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. |
| component | IDREF. | The component attribute identifies a child element of the composition, which may be a media object or another composite-object, through its id value. |
| interface | String. The default value is the whole content anchor. | The interface attribute uniquely identifies an interface (<area>, <property>, <port>, or <switchPort>) of a child element of the composition, through its id or name value. Defaults to the whole content anchor of the referred component. |