[rtcweb] RTP usage: requirement levels

Martin Thomson <martin.thomson@gmail.com> Mon, 16 July 2012 18:38 UTC

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Date: Mon, 16 Jul 2012 11:38:59 -0700
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From: Martin Thomson <martin.thomson@gmail.com>
To: rtcweb@ietf.org
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Subject: [rtcweb] RTP usage: requirement levels
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The RTP usage draft current uses MUST, SHOULD, MAY to indicate two
levels of compliance.  This is not a particularly good division for
this sort of draft.

Firstly, it's unclear what meaningful distinction there is between
SHOULD and MAY.  Then there is the distinction between MUST implement
and MUST use.

The following classifications are more relevant to this sort of draft.

mandatory to USE
 - all implementations MUST always use this feature
 - there is no reason to signal support for the feature
 - there is no reason to provide a means to disable it
 - no API requirements need to be derived for features that are mandatory to use

mandatory to IMPLEMENT
 - all implementations MUST include support for the feature
 - implementations MUST provide a means to enable and disable the
feature (API requirement)
 - there is no API requirement for indicating support of the feature

mandatory to DISABLE
 - implementations MAY include support for the feature
 - implementations MUST provide a means to signal support for the
feature (API requirement)
 - implementations that support the feature MUST provide a means to
enable and disable the feature (optional API requirement)