Exactly 1 sequences of:
Exactly 1 sequences of:
| name | Built-in type ID | required | 
                 name used to refer the item 
               | 
|---|---|---|---|
| type | required | 
                 type of the item 
               | 
|
| group | Built-in type IDREFS | required | 
                 id of the group containing the item 
               | 
| order | Built-in type int | optional | |
| required | Built-in type boolean | optional |