Specify whether to show the fixed value of the element content.
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The default value is provided by the <code>'fixed'</code> attribute of the XSD element that declares the element component.
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When the element is declared by reference, its fixed value can be specified either in the local
reference component (which is being documented here) or in the global (referenced) element component.
In that case, the <code>fixed</code> attribute is looked for in the both components.