You can "fix" certain facets by setting the 'fixed' attribute to 'true' on the facet declaration:

<length value="8" fixed='true'/>

The following facets can be fixed:

• length, minLength, maxLength

• minInclusive, maxInclusive, minExclusive, maxExclusive

• totalDigits, fractionDigits

• whitespace

Fixing a facet means a derived type cannot specify any other value than the fixed value.