[mpeg-OTspec] RE: font media types

[John Hudson]

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

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