12.1.3 Order of elements in WML file

The order of elements in the WML file is significant in these cases (and no others):

• If an element is defined more than once, the last definition takes precedence over any previous definitions. For more information, see Section 9.5, "Rules defined more than once".
• User-defined variables must be declared before being used.
• A node rule must be defined before a Heading paragraph rule may use it.