rfc-2738

Corrections to "A Syntax for Describing Media Feature Sets"

G. Klyne

date1999-12 streamIETF areaapp wgconneg statusPROPOSED STANDARD pages5 canonicalhttps://www.rfc-editor.org/rfc/rfc2738 doi10.17487/RFC2738

In RFC 2533, "A Syntax for Describing Media Feature Sets", an expression format is presented for describing media feature capabilities using simple media feature tags. This memo contains two corrections to that specification: one fixes an error in the formal syntax specification, and the other fixes an error in the rules for reducing feature comparison predicates. [STANDARDS-TRACK]

updates

rfc-2533 — A Syntax for Describing Media Feature Sets

Extracted elements (4)

design-rationale §3

Implementation experience with the RFC 2533 feature set matching rules has suggested a revised algorithm with more useful simplification rules. Apart from the corrected rule, the RFC 2533 algorithm has been implemented and shown to work as intended, but results are not always in the most convenient form; a revised algorithm is planned for future publication.

errata §2

In RFC 2533 section 4.1, the production for 'setentry' incorrectly uses '/' as a character literal separator: 'setentry = value "/" range'. The correct ABNF uses '/' as an alternative separator: 'setentry = value / range'. This fix is normative and enables set expressions like '( width=[3,4,6..17/2] )'.

errata §3

In RFC 2533 section 5.8.2, the rule '(LE f a) (GE f b) --> FALSE, a!=b' is incomplete. The corrected rule reads: '(LE f a) (GE f b) --> (LE f a), a=b; FALSE, otherwise'. This fix is non-normative (affects the feature set matching reduction algorithm).

security-consideration §4

Security considerations for this specification are discussed in RFC 2533 and related documents; this correction document introduces no new security considerations.

security