[IPP] Definition for Conditionally Required

[IPP] Definition for Conditionally Required

[IPP] Definition for Conditionally Required

wamwagner at comcast.net wamwagner at comcast.net
Mon Jul 13 16:47:33 UTC 2015


 The term " Conditionally Required" or "Conditionally Mandatory" has been used extensively, usually without a special definition. In many cases, it was not defined as a specific compliance term, but used in a context that included specifying the condition. For example, in Candidate Standard 5102.1-2003, XHTML™-Print

"Support for Inline Image Data is conditionally mandatory; i.e. any device supporting Inline Image Data shall support this method."

It was defined under compliance terminology in Candidate Standard 5100.6-2003 - Standard for The Internet Printing Protocol (IPP): Page Overrides and in Candidate Standard 5100.5-2003, Standard for The Internet Printing Protocol (IPP): Document Object

"The term CONDITIONALLY REQUIRED means that the Printer MUST support the feature, if the specified condition is true."

The term was defined in a way similar to the current definition in Candidate Standard 5110.1-2014, PWG Hardcopy Device Health Assessment Attributes.

"The term CONDITIONALLY REQUIRED is additionally defined for a conformance requirement that applies to a particular capability or feature."

Although this definition was clarified in the section of the text dealing with conditionally mandatory elements by:

"HCDs MUST support the attributes in this section if the particular capability, as described before each attribute, is implemented on the HCD."

I am unhappy with "... conformance requirement that applies to a particular capability or feature." as a general statement because:

            a. Most conformance requirements apply to a particular capability or feature. I assume that one is to infer that the requirement applies only if that capability or feature exists in the subject implementation seeking to be conformant.

            b. A requirement is conditional to an implementation because the implementation includes a particular capability or feature, but is not necessarily a requirement of the capability or feature itself, which is suggested by "applies to".

            c. In a general sense, the condition may not be the inclusion of a feature or capability. Conceivably, the condition may be how or where the implementation is used or when it was created.

There is there is the additional question as to whether the term should 'Conditionally Required" or "Conditionally Mandatory". Since the basic compliance term is "Required", "Conditionally Required" seems more appropriate.

A reasonable variation on the 2003 definition and the RFC2119 definition of requirement levels is :

CONDITIONALLY REQUIRED: definition is a requirement of the specification if the specified condition is true.

One might prefer a term other than "definition", such as capability or feature, and consider a requirement of the implementation rather than of the specification, but RFC 2119 wording  is:" … definition is an absolute requirement of the specification."

Alternatively, we could modify the current definition to:

CONDITIONALLY REQUIRED: A conformance requirement that applies if the specified condition is true.


Bill Wagner
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