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Re: Agenda, action items and suggested WOFF changes

From: John Daggett <jdaggett@mozilla.com>
Date: Mon, 10 May 2010 19:24:00 -0700 (PDT)
To: John Hudson <tiro@tiro.com>
Cc: public-webfonts-wg@w3.org, Vladimir Levantovsky <Vladimir.Levantovsky@MonotypeImaging.com>, www-font <www-font@w3.org>
Message-ID: <1792604033.159090.1273544640124.JavaMail.root@cm-mail03.mozilla.org>
John Hudson wrote:

> > 5. Add the following language to address font embedding
> >    permissions:
> ...
> > In general, it is assumed that the level of font embedding
> > permissions is set according to original font license, and that
> > web authors have made adequate efforts to make sure that the font
> > license and font embedding permission settings correspond to
> > intended use of a font on the web.
> 
> I think this sentence is problematic because it implies some kind of
> relationship between font embedding bits, the font license, and use
> of that font on the web. The concern expressed by font makers
> regarding embedding bits is that they *cannot* be assumed to
> correspond to any intended use of a font on the web.

I completely concur with this view, I think the OpenType font embedding bits
in the OS/2 table [1] should not be assumed to imply whether web use is
permitted or not.

> User Agents MUST NOT permanently install fonts delivered in a WOFF
> format as system resident fonts, and SHOULD only use downloaded
> fonts to render the content of a webpage that WOFF resources are
> associated with.

This is redundant, the CSS3 Fonts specification already defines this
behavior for *all* font types, not just WOFF [2].  See section 4.1:

  "Downloaded fonts are only available to documents that reference them,
   they must not be made available to other applications or other
   documents."

The primary reason for this is security, the content of a given page
should not influence content of a different page unless the resources
are explicitly shared (i.e. the pages link to the same resource).

> WOFF creations tools MUST verify that a font
> converted to the WOFF format does not have
> font embedding permissions set to ‘Restricted
> License Embedding’, and SHOULD generate an error
> message when this condition is encountered.
> Fonts that have “Restricted License Embedding”
> set as the only level of embedding allowed
> MUST NOT be converted to WOFF format.
 
This is implicitly inferring that "restricted license embedding"
implies "no web use"; it may be the common case but it can't be
*assumed*. For example, a font designer could decide that WOFF use via
a particular service is fine but the font shouldn't be embedded when
a webpage is printed to PDF.  Document embedding and web linking are
very distinct uses, I don't think we should blur that distinction.

I would prefer to stick with a simple declaration that the OpenType
embedding bits do not affect WOFF loading behavior, nor do they imply
whether a font can be converted to WOFF or not.  The text of font
licenses is the ultimate arbiter of whether web usage of a given
OpenType font in WOFF form is allowed.  WOFF tools shouldn't alter the
embedding bits, just as they shouldn't alter any other data in the
font data except to assure it is correctly structured (e.g. checksums
are correct).

Regards,

John Daggett

OpenType OS/2 table embedding bits:
[1] http://www.microsoft.com/typography/otspec/os2.htm#fst

CSS3 Fonts @font-face description:
[2] http://dev.w3.org/csswg/css3-fonts/#font-face-rule
Received on Tuesday, 11 May 2010 02:24:34 UTC

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