comments on chapter 2 (bidi) in CSS Writing Modes

Below are comments to the bidi chapter of "CSS Writing Modes Module Level 
3" (
http://www.w3.org/TR/2011/WD-css3-writing-modes-20110201/#text-direction) 
that I propose to send to the mailing list dealing with this document.


1) In section 2, the example should use upper case for RTL and lower case 
for Latin.
     Rationale: this is the convention used in Unicode documents like 
UAX#9. This is also the convention used in the example in section 2.3.
In the same example, the pseudo-bidi words seem meaningless. I suggest to 
use English words written backwards, like "SDROW EMOS ERA EREH".

2) Section 2, "User agents that support bidirectional text must apply the 
Unicode bidirectional algorithm to every sequence of inline boxes 
uninterrupted by a forced (bidi class B) line break or block boundary." 
should be "User agents that support bidirectional text must apply the 
Unicode bidirectional algorithm to every sequence of inline boxes 
uninterrupted by a forced (bidi class B) paragraph break or block 
boundary."
     Rationale: the status of line breaks, in particular the <br> tag, re 
bidi isolation is blurry. Paragraphs are unequivocal bidi isolators.

3) In section 2.1, the sentence "The ‘direction’ property has no 
reordering in inline-level elements whose ‘unicode-bidi’ property's value 
is ‘normal’." is not clear to me.

4) Section 2.2, in the paragraph explaining "embed": there is no need for 
a semicolon after Unicode values U+202A and U+202B.
     Rationale: they are not entities.

5) Ibidem: the description does not explain what "embed" would mean for 
block-level elements.

6) Section 2.2, in the paragraph explaining "bidi-override": there is no 
need for a semicolon after Unicode values U+202D and U+202E.
     Rationale: they are not entities.

7) In section 2.2, the order of the explanations for the values should 
rather be: normal, embed, isolate, plaintext, bidi-override, like in the 
prototype.
The current order does not seem to correspond to anything.

8) In section 2.2, the text says: "Because the Unicode algorithm has a 
limit of 61 levels of embedding, care should be taken not to use ‘
unicode-bidi’ with a value other than ‘normal’ unless appropriate. In 
particular, a value of ‘inherit’ should be used with extreme caution."
The value "inherit" has not been mentioned above as valid for the 
unicode-bidi property.
 
<end of comments> 

Shalom (Regards),  Mati
           Bidi Architect
           Globalization Center Of Competency - Bidirectional Scripts
           IBM Israel
           Fax: +972 2 5870333    Mobile: +972 52 2554160