Subject: [IPP] Media size supported clarification request for inclusion in implementers guide

From: "Zehler, Peter" <[email-masked]>
Date: Thu, 20 Nov 2014 11:58:33 +0000

All,

Based on existing implementations there appears to be some confusion around the use of the 'custom_min' and 'custom_max' name prefixes.

There are two attributes that are associated with selecting the size of media.  The first is "media" which is a type 3 keyword or name.  The associated "media-size-supported" is a set of type 3 keywords or names.  To specify a printer that supports only specific  media sizes within a given range, "media-supported" would contain the allowed values.  The list can contain standard as well as custom names.  To specify a printer supports any media within a given range the "custom_min" and "custom_max" media values are used. As long as the media supplied by the client is within the range, the job is accepted.

The other attribute for specifying media size is "media-size" which is member attribute of "media-col"  collection.  The associated "media-col-supported" is a set of "media-col".    The "media-size-supported" is sort of a database of supported media and each unique combination is explicitly enumerated.  For this reason the "media-col-supported' is specially handled when getting the printer's attributes.  To specify two different supported sizes and example would be {{x-dimension:210, y-dimension:297},{x-dimension:297, y-dimension:420}} to show that it supports two values of "mediasize": A4 (210x297) and A3 (297x420).  It does not support other combinations of "x-dimension" and "y-dimension" member attributes, such as 210x420 or 297x297, and it does not support non-enumerated values, such as 420x595.

The mistake that has been seen in implementation in the field is that when a supported size range is specified, not all the media sizes within that range are actually supported.

Pete

Peter Zehler

PARC, A Xerox Company
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