Interface PrintRequestAttribute is a tagging interface which a printing
attribute class implements to indicate the attribute denotes a
requested setting for a print job.
Attributes which are tagged with PrintRequestAttribute and are also tagged
as PrintJobAttribute, represent the subset of job attributes which
can be part of the specification of a job request.
If an attribute implements DocAttribute
as well as PrintRequestAttribute, the client may include the
attribute in a Doc
}'s attribute set to specify
a job setting which pertains just to that doc.