Re: [PATCH] Unicode: update of combining code points

From: Peter Krefting <peter@softwolves.pp.se>
Date: Apr 24, 2014, 09:02 UTC
Message-ID: <alpine.DEB.2.00.1404240949440.28469@ds9.cixit.se>
In-Reply-To: <534E0B84.6070602@web.de>

Torsten Bögershausen:

> Some of the code points which have "0 length on the display" are called
> "combining", others are called "vowels" or "accents".
> E.g. 5BF is not marked any of them, but if you look at the glyph, it should
> be combining (please correct me if that is wrong).

All combining characters has a non-zero combining class in http://www.unicode.org/Public/UNIDATA/UnicodeData.txt (fourth field, called Canonical_Combining_Class in http://www.unicode.org/reports/tr44/ ). For instance, the aforementioned U+05BF is defined as follows:

   05BF;HEBREW POINT RAFE;Mn;23;NSM;;;;;N;;;;;

The combining class is 23, so this is a combining character.

There is a difference between non-spacing combining marks ("Mn" in the third column (General_Category)) and others ("Mc" for spacing marks and "Me" for enclosing marks), so they might need specifial handling. Additionally, you have the "zero-width" characters, such as U+200B Zero Width Space. These have the "Cf" class, although it also contains visible characters IIRC.

-- 
\\// Peter - http://www.softwolves.pp.se/