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Re: textDecoration question

From: Glenn Adams <glenn@skynav.com>
Date: Sun, 12 May 2013 18:49:31 -0600
Message-ID: <CACQ=j+fQ9ETOwULt-e2xcOG3Evjso+zB1C1-41FATNZWwLkeLw@mail.gmail.com>
To: Michael A Dolan <mdolan@newtbt.com>
Cc: public-tt <public-tt@w3.org>
On Fri, Jun 22, 2012 at 6:00 PM, Michael A Dolan <mdolan@newtbt.com> wrote:

> The prose for this attribute is not clear whether combinations of the
> pairs of attributes can be used.  The examples show only a single value at
> a time – e.g. either underline or lineThrough.****
>
> ** **
>
> The syntax is constructed in an unusual manner if the intent was to only
> permit a single value.  The schema is currently an enumeration, forcing
> only a single value.
>

To understand the notation, you have to trace back to XSL-FO and thence to
CSS 2. See [1].

[1] http://www.w3.org/TR/CSS2/about.html#value-defs

Specifically:

A double bar (||) separates two or more options: one or more of them must
occur, in any order.

This would probably be more clear if someone hadn't removed the references
to the XSL-FO definitions upon which the properties were based, though you
can still trace it via Appendix J.2 Attribute Derivation [2].

[2]
https://dvcs.w3.org/hg/ttml/raw-file/default/ttml10/spec/ttaf1-dfxp.html#attribute-vocab-derivation-table

In any case, the intent is *not* to permit a single value, e.g., "underline
overline noLineThrough" is a valid value.

****
>
> ** **
>
> If the schema is correct, then one can never apply both underline and
> lineThrough concurrently – e.g. textDecoration=”underline lineThrough”.***
> *
>
> ** **
>
> Does the schema reflect the intent?  If so, then why the odd construction
> of the syntax in the prose?****
>
> ** **
>
> Thanks,****
>
> ** **
>
>                 Mike****
>
> ** **
>
> Michael A DOLAN****
>
> Television Broadcast Technology, Inc****
>
> PO Box 190, Del Mar, CA 92014 USA****
>
> +1-858-882-7497 (m)****
>
> ** **
>
Received on Monday, 13 May 2013 00:50:41 UTC

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