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[CSS21] WD 6.1.1, 6.2.1: 'inherit' as specified value (was: Editorial issues with Ch. 6 (Assigning property values, Cascading, and Inheritance) - comments on Working Draft

From: Peter Moulder <peter.moulder@monash.edu>
Date: Fri, 07 Jan 2011 23:47:23 +0000
To: "www-style@w3.org" <www-style@w3.org>
Message-id: <20110107234723.GL21438@bowman.infotech.monash.edu.au>
On Fri, Jan 07, 2011 at 09:46:26PM +0100, Anton Prowse wrote:
> Issue 1: 6.2 Inheritance says:
> 
>   # When inheritance occurs, elements inherit computed values. The
>   # computed value from the parent element becomes both the specified
>   # value and the computed value on the child.
> 
> This is not the case when the keyword 'inherit' is used, though.  In
> that case, the specified value is 'inherit', which is never the same
> as the computed value.

(I'm posting this as a followup because it's much the same issue as Anton
identifies above.  I wrote this text before Anton posted, so there's a
little overlap.)

6.1.1, can specified value be 'inherit':

  I suggest changing 6.1.1 such that the "specified value" is never
  'inherit'.
  Various places in the spec talk use the phrase "specified value" as if
  it meant "specified or default or inherited value as applicable"; I
  suggest changing the definition to match.

  The phrase "as specified" in "Computed value" fields is the same.

  The only places I know of that take 'inherit' to be a specified value
  are 6.1.2 para 3, and 6.2.1.

  A somewhat related existing issue that can be addressed as part of
  this change is the text "As specified" for "Computed value",
  which is of course intended to mean "equal to the specified value"
  in the sense above (i.e. never 'inherit').

  Accordingly, I suggest changing the rule of 6.1.1 to add the condition
  "other than 'inherit'"; and changing 6.2.1 to remove its second
  paragraph, and change the first paragraph to describe how 'inherit'
  is useful rather than how it behaves: e.g. simply remove the first
  sentence while leaving the second.

  A new paragraph could be added that refers the reader to 6.1.1
  (#specified-value) for its behaviour.


  One concern I have with this change is that it widens the gap between
  the intuitive meaning of "specified value" and its technical meaning.
  (Already there is something of a gap in the case that the cascade
  doesn't yield a value.)

  Is there a better phrase to use?  "Requested value" ?
  "Cascaded value" ?

  Regardless of the name chosen, I suggest making sure that all
  occurrences of the phrase link to this definition, to make
  it clear that the phrase is used in this technical sense.

  Similarly, the phrase "as specified" in Computed value fields should
  link to a paragraph in this section that defines the phrase as
  referring to this specified/default/inherited value.

pjrm.
Received on Friday, 7 January 2011 23:47:54 GMT

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