Whitespace in anyURI

The constraining facet whiteSpace for anyURI in the Schema for Datatype
Definitions is given as collapse.

This constrains the values of anyURI to exclude #xA, #xD, #x9 and
consecutive pairs of #x20; as well as initial and final #x20.

These constraints are not however clearly articulated in the definition of
anyURI. For example, the XLink text for the value of the attribute
xlink:href does not exclude any of these (remembering that attribute value
normalization can be circumvented by the use of character references). Note
that in the Sample DTD for [XLink], xlink:href has attribute type CDATA.

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I suggest that the lexical and value space of anyURI should be clarified to
fold in the constraints from the whiteSpace facet.

Jeremy Carroll