PPDs, IPP requests and user defined values

Many printers (high end production printers especially) allow to specify
arbitrary
values for certain features, e.g. media types, media weights, or media
colors.
For example, it may be valid PostScript (and correctly honoured by the
printer)
to specify
        <</MediaType (my company's letterhead for VI customers)>>setpagedevice
But neither the PPD (as ov version 4.3 of Adobe's PPD spec) nor IPP
provide for
user defined values like this (the printer I'm silently thinking of only
tells
media-color-supported = "no-color" "white" "pink" "yellow" "blue"
"green" "buff" "goldenrod" "red", which are the same values as specified
in the vendor's PPD.

Are there any plans for CUPS to allow such option values (and, if yes,
how)?

Helge

-- 
Helge Blischke
Softwareentwicklung
SRZ Berlin | Firmengruppe besscom
http://www.srz.de
tel: +49 30 75301-360