====== UTR #50 Review Memo ======
This page is a memo page to make our discussion on [[http://www.unicode.org/reports/tr50/|UTR #50]] smooth.

===== Open Issues =====

[[:spec:utr50:agenda|Tracking open issues, or resolved issues not yet published in an update]]

===== Analysis by Codepoint =====

Two modes are presented: Stacked (''text-orientation: upright'') and Mixed (''text-orientation: mixed''). Codes used for analysis by codepoint:

^Code^Meaning^
^U|Upright; translates between horizontal and vertical|
^R|Sideways; rotates between horizontal and vertical|
^T<sub>U</sub>|Typeset upright with alternate glyph. Best fallback is just upright.|
^T<sub>R</sub>|Typeset upright with alternate glyph. Best fallback is just sideways.|
^V|Upright wrt Unicode code charts, but translates between horizontal and vertical (VO=U/HO=L)|

Codepoint classifications and notes by general category:

  * [[spec:utr50:letters|Letters (L*) and Numbers (N*)]]
  * [[spec:utr50:punctuation|Punctuation (P*) and Spaces (Z*)]]
  * [[spec:utr50:symbols|Symbol, Modifier (Sk)]]
  * [[spec:utr50:symbols:currency|Symbol, Currency (Sc)]]
  * [[spec:utr50:symbols:math|Symbol, Math (Sm)]]
  * [[spec:utr50:symbols:currency|Symbol, Currency (Sc)]]
  * Symbol, Other (So)
    * [[spec:utr50:symbols:textual]]
    * [[spec:utr50:symbols:pictographs]]
    * [[spec:utr50:symbols:cjk]]
    * [[spec:utr50:symbols:enclosed]]
    * [[spec:utr50:symbols:ancient]]
    * [[spec:utr50:symbols:game]]
    * [[spec:utr50:symbols:technical]]
    * [[spec:utr50:symbols:drawing]]
  * [[spec:utr50:symbols:arrows]] (So and Sm)
  * [[spec:utr50:control]]

Potential tailoring categories:
  * [[spec:utr50:symbols:arrows|Arrows]]
  * Math relational operators (equals, greater-than, etc)
  * SB brackets

===== Comparisons =====

  * [[spec:utr50:diff20120609|Differences against the current draft]]
  * [[http://blog.antenna.co.jp/CSSPage/tr50-taro.20120712.html|Comparison of UTR50 and Yamamoto-san's proposal]]
===== Notes on Interaction with Font Design =====

  * From what I understand, T allows anything; from changing glyph to changing orientations, so although "representative glyphs" are shown, their orientations are undefined in UTR #50. Some rotate, some do not, and it's up to font designer. Is this correct understanding?
  * If UTR #50 means fonts should not change glyphs/positions for U/S/SB, there are compatibility and font designing problems here.
    * Some fonts use different glyphs for parenthesis/brackets in vertical  flow; e.g., U+FF62/FF63. {{ :spec:kodomonoji_20111005-en.png?linkonly|}}
    * Some fonts use U+301D/301F glyphs for U+201C/201D in vertical flow.
    * Some fonts use GPOS to adjust positions of punctuation in vertical flow.
    * For brush-stroke fonts, start and end edges of strokes (起筆/収筆 in Japanese) vary by flow direction for several glyphs, just like it does for U+30FC, because the direction brush moves is different; e.g., {{:spec:suzuedo.png?linkonly|}}
  * Issues with non-square fonts:
    * U does not work with proportional or non-square fonts. If a font is condensed (tall) in horizontal flow, it needs to be condensed (wide) in vertical flow; e.g., [[http://www.axisfont.com/|AXIS fonts]]
    * S/SB does not work with slanted fonts; e.g., {{:spec:susha.png?linkonly|}}
  * Does the baseline alignment work good by just rotation?
    * EM DASH, Arrows, etc. aligns at center baseline?
    * Most font designers I contacted believe that it's ok as long as the font is a square font, but I'm worried as it has never been tested at all.

===== Potential Tailorings =====

  * upright-cyrillic
  * upright-greek
  * upright-latin
  * upright-letterlike
  * sideways-symbols
  * upright-math
  * upright-numeric
  * sideways-unified-punctuation-type-stuff?

===== Historical ======

  * [[http://lists.w3.org/Archives/Public/www-international/2011OctDec/0034.html|Comments from CSS3 Writing Modes editors to Unicode circa October 2011]]
  * [[http://www.unicode.org/forum/viewtopic.php?f=35&t=202|Vertical Directionality property from johnwcowan]]
  * [[http://lists.w3.org/Archives/Public/public-i18n-cjk/2011OctDec/0000.html|Hangul characters upright or sideways in vertical flow?]]
  * [[http://lists.w3.org/Archives/Public/www-style/2011Oct/0128.html|Yi and Hangul]]
  * [[http://lists.w3.org/Archives/Public/www-style/2011Oct/0374.html|Egyp]] also [[http://www.omniglot.com/writing/egyptian_hieratic.htm|Hieratic]] does not rotate