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RE: Tabs in CSS1

From: Stefan Olson <stefan@olsonsoft.co.nz>
Date: Thu, 21 Nov 1996 09:49:30 +1300
Message-ID: <01BBD791.526681E0@ppp66-001.manawatu.gen.nz>
To: "'Dave Raggett'" <dsr@w3.org>
Cc: "'www-style@w3.org'" <www-style@w3.org>
>>> I would like to see support for tabs added into the CSS
> spec ... Are there any plans to add this in? 

There has been discussion about this for future enhancements
to CSS. One approach is define tab rule property with the ability
to set tab stops at particular positions, differentiating between
left, center, right and "decimal" tabs.<<

Good point - in my example I forgot to add the ability to set the
tab stop type - this is quite important.

>>A horizontal tab character then moves the output position to 
the next tab stop. Instead of the '\t' char you could require an SGML 
entity or an element, e.g. <tab align=right>.<<

Given the fact that the alignment of the tab stop is set in the rule
properties, what is the need for an align value in the tab tag?  Maybe
you are suggesting that you could perhaps align text between
two tab stops?

>>One issue is whether there should be a default tab rule with
tab stops at regular intervals, and whether when you move past
the last tab stop on an explicit rule, you then see the default
tab stops.<<

I think on issues like this it is best to look at tools that already
support tabs, such as the major word processors/desktop publishers.
In these products you always have a default tab rule (normally at
0.5in between tabs), and you always jump to the next explicit tab
stop.  If such a stop is not available then you should jump to the
next default tab stop.  Thus in the answer to your question is yes,
you should see the default tab stops.

>>Another issue is what to do when the output position
is already to the right of the next tab stop: should the tab be
treated as if it werer a single space character, or should you
skip to the next defined tab stop (which may well be of a different
type e.g. a decimal tab stop rather than a left tab stop).<<

You should move to the text tab stop.  It is really up to the author to
try and avoid these issues.  If he/she thinks that when a user re-sizes
the display surface or displays the page on a different display surface
than designed for things may not look quite right (as in your situation)
then he/she should be using tables.

In the market I am in, I know our customers are likely to be displaying
their files on a Windows PC, and thus that explicit tab stops will always 
work correctly.  As I don't use other machine types, I'm not sure how
a file with explicit tab stops (perhaps in inches) would appear.

>>How should tab rules be interpreted for lines with mixtures
of left to right and right to left character sequences?<<

This is a very good point, and I do not have a great understanding of
these multi-lingual issues. However, I did take a look at the Accent 
word processor working demo (http://www.accentsoft.com) and found 
a couple of interesting things:
1) If text is not justified in the normal text direction manner (e.g: left
for left to right and right for right to left) tabs are treated as spaces.  
This is sensible enough - Microsoft Word does a very bad job of
handling tabs in paragraphs that are not left justified.
2) That the tab stops are based on the overall paragraph direction.  So,
if you have a right to left paragraph then all tabs will be right to left, even
if you have put a tab in a bit of text that is left to right.  Therefore, that
may be one way to resolve this issue for HTML.

I hope this helps.

Cheers,
Stefan
Received on Wednesday, 20 November 1996 15:50:41 GMT

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