[Issue 1] Re: [Ietf-calsify] draft-ietf-calsify-rfc2445bis-01.txt / UTF-8

Mark Crispin mrc at CAC.Washington.EDU
Mon Sep 11 09:46:38 PDT 2006

On Mon, 11 Sep 2006, Sam Roberts wrote:
> Quoting lists at block-online.eu, on Sat, Sep 02, 2006 at 12:29:25PM +0200:
>> Am Freitag, 1. September 2006 18:32 schrieb Mark Crispin:
>>> Therefore, a better wording is:
>>> ----------------------------------------------------------------------
>>> Folded lines MUST be well-formed according to the character set specified
>>> for the iCalendar object.  Folding MUST NOT occur between octets that
>>> define a single codepoint in a character set that uses multiple octets to
>>> define a codepoint (e.g., non-ASCII codepoints in UTF-8, East Asian
>>> character sets).  [Furthermore, folding MUST NOT occur prior to a
>>> codepoints that defines a combining character.]  This may require
>>> folding a line at less than the recommended 75 octet limit.
>>> ----------------------------------------------------------------------
> Is the "[Furthermore,...combining character.]" text supposed to be part
> of the the wording?

This is a matter under discussion.  The text is in a [] pair since its 
inclusion depends upon the decision of the WG.

> It appears that there are combining characters defined in many blocks of
> unicode characters.
>  http://www.unicode.org/faq/char_combmark.html
> How do I determine that a code point defines a combining character? Is
> there a list of such code-points?

You don't determine combining character by codepoint value.  You determine 
it by the codepoint's Canonical Combining Class value, as defined in the 
UnicodeData.txt file.  Characters with a Canonical Combining Class value 
of 0 are not combining characters.

-- Mark --

Democracy is two wolves and a sheep deciding what to eat for lunch.
Liberty is a well-armed sheep contesting the vote.

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