[mpeg-OTspec] RE: font media types

Levantovsky, Vladimir vladimir.levantovsky at monotypeimaging.com
Tue Apr 5 21:26:18 CEST 2011

Thank you John,

I believe making a distinction based on the types of glyph outline data has always been the primary goal, and what you proposed seem to make perfect sense. However, I'd like to keep an "umbrella" media type to separate OpenType/OFF-based SFNT objects vs. arbitrary SFNT-based format.

Strictly speaking, defining a media type for an arbitrary SFNT-based format would go beyond the scope of ISO OFF specification, but I think it would be acceptable to attempt to define this media type as part of the ISO document anyway, to offer a way to distinguish SFNT font structures that are not compliant with the ISO standard (and we know there are many of them out there). With this in mind, would the following be acceptable to everyone:

- application/font-ttf - for traditional TrueType fonts and OpenType/OFF fonts with TrueType outlines;
- application/font-cff - for OpenType/OFF fonts with CFF outlines;
- application/font-off - for OpenType/OFF fonts with both TrueType and CFF outlines, or as a generic type for a font that is compliant to ISO OFF spec, and
- application/font-sfnt - for generic SFNT-based font formats.

Please voice your objections / concerns / comments / agreement - I need to finalize the text of the annex and submit it to ISO SC29 by the end of the week.

Thank you,

> -----Original Message-----
> From: John Hudson [mailto:john at tiro.ca]
> Sent: Tuesday, April 05, 2011 2:08 PM
> To: Levantovsky, Vladimir
> Cc: David Lemon; OTspec; Chris Lilley; Tab Atkins; Karsten Luecke
> Subject: Re: [mpeg-OTspec] RE: font media types
> Vladimir wrote:
> > We can also consider changing the proposed
> > media types, e.g. to be more specific and use font-ttf, font-cff and
> > font-otf for the purposes outlined above.
> If the distinction is to be based on outline type, then I think
> 'font-ttf' and 'font-cff' is much preferable to using 'font-otf' for
> the
> latter. The only reason .otf is not typically used as a file extension
> for TrueType fonts is so that the latter are backwards compatible with
> older Windows systems that do not recognise .otf; this is obviously
> less
> of a practical concern than it was in 1998, and now persists mostly as
> convention. I have, however, seen some TrueType fonts with an .otf
> extension.
> OTF stands for OpenType Font, not PostScript OpenType Font, and the
> first item in the OpenType catechism is that an OpenType font may
> contain either TrueType or PostScript outlines. Hence, I think it is
> misleading or at least confusing to identify 'font-otf' with PostScript
> outlines.
> I also wonder about using either 'font-off' or 'font-otf' to indicate
> an
> unknown outline type: the former because OFF is not a widely used or
> recognised abbreviation -- the Open Font Format being reasonably seen
> as
> a particular publication of the OpenType Font specification --, and the
> latter because of potential confusion in the minds of those who, due to
> convention, associate .otf with PostScript outlines.
> I wonder if there might be grounds for a generic 'font-sfnt' MIME type,
> which would not only express the desired agnosticism regarding outline
> type, but would also be useful for fonts containing non-OTL layout
> tables.
> So we might have:
> 	application/font-ttf
> 	application/font-cff
> 	application/font-sfnt
> JH
> --
> Tiro Typeworks        www.tiro.com
> Gulf Islands, BC      tiro at tiro.com
> A pilgrimage is a journey undertaken in the
> light of a story. -- Paul Elie

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