Specifying That an Element is Optional in DTDs

You specify that an element is optional when you add a reference to that element in another element. When an element is optional, it means that there can be one or none. If you want to specify that there can be none, one, or more, use the Zero or More modifier. See Specifying That Multiple Instances of An Element Are Allowed in DTDs.

In the Tree tab, to specify that an element is optional:
1. Define the element that you want to be optional. See Defining Elements in the DTD Tree Tab.
2. Create the element that contains the element that you want to be optional. This is the container element.
3. Click the container element name.
4. In the tool bar on the left, click New Modifier . Stylus Studio displays a drop-down menu.
5. If the container element can contain only the optional element, skip this step. If the container element can contain more than one element, click Sequence.
6. Click New Modifier.
7. In the pop-up menu that appears, double-click Optional.
8. In the tool bar on the left, click New Reference to Element and enter the name of the optional element. If the container element can contain additional optional elements, repeat this step for each one.

After you add a reference to an element, you might want to check the definition of the referenced element. To do this, right-click the reference. In the shortcut menu, click Go To Definition. Stylus Studio moves the focus to the definition of the referenced element.

 
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