I would suggest a clarification to the language below. Ultimately,
"read-only" is a taste issue for some attributes.
A Printer vendor is allowed to set an attribute to be read-only if an
attribute can have only one value for the life-time of the printer. But a
Printer vendor need not set such an attribute to be read-only. The
following are examples where read-only is not suitable:
The sides-default can only have the value "one-sided" because an admin
set
sides-supported to "one-sided" only.
The sides-supported attribute can only have the value "one-sided"
because the
duplexer has not yet been installed. But when it is installed,
side-supported
can also have the value "two-sided-long-edge".
It would be OK for "sides-supported" and "sides-default" to be read-only for
a Printer which a vendor never intends to sell a duplexer for. It would also
be OK for this Printer to have both of these attributes be writeable with
"one-sided" being the value, as specified by the factory setting of
"sides-supported".
Bob Herriot
-----Original Message-----
From: Hastings, Tom N [mailto:hastings at cp10.es.xerox.com]
Sent: Tuesday, January 11, 2000 4:08 PM
To: ipp
Subject: IPP> OPS - comment: Clarifying READ-ONLY and one supported
value
At the December IPP WG meeting, we agreed that an "xxx-supported" attribute
that has only one value SHOULD be a READ-ONLY attribute. However, I think
we meant if the implementation *as reflected in the factory settings* has
only one value. Therefore, the following statement that was added to the
Set spec needs clarification:
For a Printer attribute that is normally settable, if a Printer object only
supports a single fixed value for that attribute, it SHOULD NOT include that
attribute's keyword name in this attribute's value. For example, if a
Printer only supports "sides" with a 'one-sided' value, then the
"sides-supported" keyword SHOULD NOT be one of the values of its
"printer-settable-attributes" attribute.
I suggest the following update to the "printer-settable-attributes"
attribute:
For a Printer attribute that is normally settable, if a Printer
implementation only supports a single fixed value for that attribute, it
SHOULD NOT include that attribute's keyword name in this attribute's value.
For example, if a simplex output device only supports "sides" with a
'one-sided' value, then the "sides-supported" keyword SHOULD NOT be one of
the values of the IPP Printer's "printer-settable-attributes" attribute.
However, if an administrator changes an "xxx-supported" attribute to a
single value, that attribute SHOULD NOT become READ-ONLY and that
attribute's keyword name SHOULD NOT be removed from the
"printer-settable-attributes" attribute.