Problems of ISO/IEC 26300 in handling Kihon-hanmen

[MURATA Makoto (FAMILY Given)]

Folks,

15.2.21 Layout Grid is intended to provide "Asian layout grids".  Unfortunately, 
it provides something different from Japanese requirements as described in 
"Requirements for Japanese Text Layout", W3C Working Group Note, 4 June 2009, 
available at http://www.w3.org/TR/jlreq/.

>The exact 
>number of lines depends on the other grid layout properties described below. There is no 
>space between the layout grid lines. 

No.  The number of lines should come first.   See (e) in 2.2.4.
http://www.w3.org/TR/2009/NOTE-jlreq-20090604/#en-subheading1_1_4

> There is no space between the layout grid lines.

No.  See (f) in 2.2.4 http://www.w3.org/TR/2009/NOTE-jlreq-20090604/#en-subheading1_1_4

>The layout grid itself is centered on the page

Just one way to do so.  Not good enough.
See (b) in 2.2.4 http://www.w3.org/TR/2009/NOTE-jlreq-20090604/#en-subheading1_4_1

>both: Like lines, except that the lines are divided into square cells. The number of cells per 
>line depends on the line height, where the line height is the sum of the base height and the 
>ruby height as specified below. 

Again, the line gap should come first.  Ruby should fit in the gap.  More about this, see note 1 
in (d), ”2.4.2 Considerations in Designing the Kihon-hanmen", available at 
http://www.w3.org/TR/jlreq/#en-subheading1_4_2

>Within a layout cell, nor more than one Asian [UNICODE] 
>character is displayed. Asian characters that do not fit into a single cell are displayed centered 
>into as many cells as required. Non Asian text is centered within as many cells as required.

This is a very common misunderstanding.  A note in the Japanese version of the W3C "Requirements 
for Japanese Text Layout" is quite clear about this point.  It clearly says that "After you determine 
the kihon-hanmen parameters, it is not at all necessary to consider the grid while positioning characters."
It even says that the slit model is better than the grid model in understanding Japanese typography.
Unfortunately, the English version does not have this note.

Cheers,
Makoto