The element element can be used either
at the top level to define an element-type binding globally,
or within a content model to either reference a globally-defined
element or type or declare an element-type binding locally.
The ref form is not allowed at the top level.
The element element can be used either at the top level to define an element-type binding globally, or within a content model to either reference a globally-defined element or type or declare an element-type binding locally. The ref form is not allowed at the top level.