Re: metric for block coverage

On 2018-02-18 12:10, Richard Wordingham via Unicode wrote:

>> It's only a single bit without a meaning beyond "range is considered
>> functional". No "basic coverage" vs "good coverage" vs "full
>> coverage".
> It's worse than that when a script uses characters primarily
> associated with another script. For example, to have any confidence
> that my Tai Tham font will be used for U+0E4A THAI CHARACTER MAI
> TRI or U+0E4B THAI CHARACTER MAI CHATTAWA placed on U+1A4B TAI THAM
> LETTER A, I have to set the Thai bit, even though I only have four Thai
> characters in my font. (The other two are punctuation.)
>

Indic scripts (other than Devanagari) also use a few characters from
another block. Specifically, two punctuation characters (from the
Devanagari block)

  * U+0964 DEVANAGARI DANDA
  * U+0965 DEVANAGARI DOUBLE DANDA

are expected to be used with the non-Devanagari Indic scripts. Looking
at the fonts Noto Sans Kannada and Noto Sans Tamil, the expected Unicode
range bit is set for Kannada or Tamil, but not Devanagari, even though
those fonts contain U+0964 and U+0965.

Bobby

-- 
Bobby de Vos
/bobby_devos_at_sil.org/