2.1.1 [W3C-XSS] Section 3.3.1, The Element Declaration Schema Component

  • Article

V0001:

The specification states:

 {value constraint} establishes a default or fixed value for an element. If 
 default is specified, and if the element being ·validated· is empty, then the 
 canonical form of the supplied constraint value becomes the [schema normalized 
 value] of the ·validated· element in the ·post-schema-validation infoset·. If 
 fixed is specified, then the element's content must either be empty, in which 
 case fixed behaves as default, or its value must match the supplied constraint 
 value.

MSXML6

If an element that is being validated includes a {value constraint} value that is specified as default and the element is empty, the default value is not supplied.