W3C home > Mailing lists > Public > whatwg@whatwg.org > December 2007

[whatwg] "must only" ambiguity

From: Krzysztof Żelechowski <giecrilj@stegny.2a.pl>
Date: Thu, 27 Dec 2007 17:26:22 +0100
Message-ID: <1198772783.6520.8.camel@a1dmin.vola.spe.com.pl>

Dnia 24-12-2007, Pn o godzinie 16:36 -0500, L. David Baron pisze:
> On Monday 2007-12-24 19:07 +0100, Krzysztof ?elechowski wrote:
> > My rewording for competition: 
> > "Authors may use elements in the HTML namespace 
> > in the contexts where they are explicitly allowed and nowhere else."
> 
> > My rewording for competition: 
> > "Authors may put elements inside an element only if that element..."
> > (because "only if" is a common and well understood expression.)
> 
> These won't work because they make the statement a much weaker
> requirement per RFC 2119:
> http://www.ietf.org/rfc/rfc2119.txt
> 
> Changing from a MUST or MUST NOT to a MAY is a substantive change,
> not a rewording.

RFC 2119 does not forbid using MAY conditionally.  Under these
conditions, this is a MAY, otherwise this is a MUST-NOT.  If you prefer
MUST NOT to MAY NOT, which is about the same in English, you can say
"... and MUST NOT use them anywhere else."

Note that this is a true MAY, not a MUST; you NEED NOT use any HTML
elements at all, except for a few that make the basic skeleton of a
document, and I may even be wrong here because those elements may be
supplied by the user agent so that an empty document is a valid
document; but that MUST is described elsewhere, and I may even be wrong
here because those elements may be supplied by the user agent so that an
empty document can be treated as valid.

Chris
Received on Thursday, 27 December 2007 08:26:22 UTC

This archive was generated by hypermail 2.3.1 : Monday, 13 April 2015 23:08:38 UTC