Re: UAX #14: no line breaks between OP and QU, even if there are intervening spaces

Arnt Richard Johansen wrote:

> In UAX #14, rule LB15 states "Do not break within '"[', even with
> intervening spaces." This is formalised as
>
>     QU SP* × OP
>
> What is the rationale behind this rule?

Beats me. Whatever the rationale might be, the rule is harmful more 
often than useful. I'm afraid the line breaking rules as a whole just 
try too much: they define detailed rules for combinations, based on the 
consideration of some _possible_ scenarious where the combinations might 
appear.

> As an example, given a sufficiently small text area width, the
> algorithm will break text this way:
>
>     "The
>     Wire" (2005)
>
> but never this way:
>
>     "The Wire"
>     (2005)
>
> which is IMHO more logical.

Unfortunately, this isn't just theoretical. At least Internet Explorer 
does this, both for ASCII quotation marks and for English quotation 
marks. And IE does not adequately support Unicode control characters for 
allowing line breaks, so the only cure is really the use of nonstandard 
markup, the <wbr> tag (oddly named, since it does not indicate _word_ 
break but an allowed string break).

To take another example that has caused real trouble, consider LB19, 
which prohibits line breaks before or after quotation marks. This is 
nasty because it prevents a break before a "quoted" expression inside a 
sentence, and at least some versions of Microsoft Word take this 
seriously.

Line breaking rules are strongly language- and context-dependent, and 
they shouldn't really be part of the Unicode Standard, except for some 
very basic principles like the special controls for line break. The UAX 
#14 rules are probably based on _some_ rational considerations but 
oriented towards some largely unspecified situations. There is probably 
a lot of language and context dependency hidden in them. And I don't the 
rules have generally been implemented, but they have _partly_ been 
implemented in various programs

Jukka K. Korpela ("Yucca")
http://www.cs.tut.fi/~jkorpela/


Jukka K. Korpela ("Yucca")
http://www.cs.tut.fi/~jkorpela/