Bopomofo light tone mark on the Web

Philippe Verdy verdy_p at
Wed Feb 4 19:45:48 CST 2015

Does it really matter, given that the sign is written orthogonally
direction of writing of the bopomofo line ? Does it have to be a combining
character when it could be a standard spacing character on that line so
that users can place it before or after (for collation it would be a
problem only for the ternary level, but it can be ignorable in the first
and second level).
Wouldn't the common middle dot be usable ?
Or could a variant be encoded after the specific Bobomofo light tone
spacing mark, to indicate its preferred placement ("above" or "below",
probably with '"above" being the default) in the vertical writing style
(this variant being ignored for the horizontal writing style for example in
IME) ?

2015-02-04 13:40 GMT+01:00 Richard Ishida <ishida at>:

> At the W3C we are trying to understand how to handle the bopomofo in
> phonetic annotations (for the CSS Ruby spec).
> Please see a write up of the background and some relevant questions at
> A key question relates to the light tone.
> The light tone falls out from most IMEs and is displayed, for example, by
> Keynote's phonetic guide function, after the bopomofo letters. In pretty
> much all the vertical bopomofo we have seen, and in pretty much all
> dictionaries we have seen (horizontal or vertically set) the light tone,
> however, is displayed before the bopomofo letters.
> Note that modern dictionaries appear to be actually moving the character
> code into first position in the syllable to achieve this.
> We'd like to know:
> 1. is anyone aware of any ruling about where the light tone should appear
> and/or be stored in the text stream?
> 2. does it (really) matter if text sometimes contains the light tone
> character  before the syllable and sometimes trailing, depending on where
> people prefer to put it?
> (Obviously, there's a theoretical issue for sorting and searching if it is
> sometimes in one place and sometimes in another, but it may be that both
> places are actually viable positions.)
> 3. is there any font/rendering software out there that makes the light
> tone appear at the start of a syllable, when the character is actually at
> the end of the syllable?
> cheers,
> ri
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> Unicode at
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