Sets the media size that is to be used in place of the
currently requested media size.
Additional information:
When a request is received to print on a size and
type of media that is not currently available, this object contains the
desired size as set by the print job. This object should be set to a media
size that is currently available to the printer.
If a paper mount request is not pending, attempting to get or set this object
will cause <noSuchName> to be returned.