From: Chris Jacobs (chris.jacobs@freeler.nl)
Date: Sat Aug 02 2003 - 15:27:33 EDT
----- Original Message -----
From: "Theodore H. Smith" <delete@elfdata.com>
To: <unicode@unicode.org>
Sent: Saturday, August 02, 2003 12:32 PM
Subject: Questions on ZWNBS
> Hi list,
>
> I have some questions on the ZWNBS. While I don't actually need this
> myself, someone I know needs this.
>
> > Where? Specifically, where does it say FEFF shouldn't be in a string?
It does not say that.
> > Certainly, FEFF shouldn't be considered a BOM anywhere but at the start
> > of a string, but does it say you just can't use that value? And if so,
> > how are you supposed to use a ZWNBSP?!
> I'm thinking that 0xFEFF shouldn't be in a UTF16BE string, except at
> the start right?
Wrong!
U+FEFF has two different uses, ZWNBS and BOM
In a UTF-16BE string (and also in a UTF-16LE string) it is _always_ a ZERO
WIDTH NO-BREAK SPACE, and _never_ a BOM, regardles if it is at the beginning
of the file or not.
Not that there is much use for a ZWNBS at the beginning of a file, but
suppose that jou have a routine that removes BOM's at the beginning of
files. Then it should _not_ remove a ZWNBS at the beginning of a UTF-16BE
text, even though a ZWNBS there makes no sense.
> For other kinds of UTF, I'm not sure if it is allowed or not. I know it
> is allowed in UTF16LE. although discouraged.
>
> Instead of "can't use ZWNBS", I think that char is discouraged. Where
> is the rule that discourages it?
The use of U+FEFF as ZWNBS is afaik not discouraged.
As for the use UTF-16 with BOM I cannot cite a rule which
discourages it, but it is something I would expect to be discouraged. Using
UTF-16BE or UTF-16LE instead is much simpler.
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