Re: Impossible combinations?

From: John Hudson (
Date: Sun Mar 02 2003 - 21:08:46 EST

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    At 04:11 AM 3/2/2003, Kevin Brown wrote:

    >I'm working on a Latin-based font that's got a large number of kerning
    >pairs already defined and I'm trying to pare this list of pairs down to
    >the bare minimum. There seem to be many pairs which are unlikely ever to
    >be used. These pairs all involve a lowercase on the left with an
    >uppercase on the right.
    >My intuition is to delete all such pairs but since I am not a linguist I
    >thought I'd better check first. Does anyone know of a Latin-based
    >language in which it is possible to have a lowercase immediately followed
    >by an uppercase in the SAME word?

    This is not uncommon in some of the Bantu languages; I can't remember which
    ones, but at least one major regional language in southern Africa.

    You should be aware that there are lots of applications that gag on large
    numbers of kerning pairs. Thomas Phinney in the type group at Adobe advised
    us that 3,000 standard kern pairs is about the maximum one can expect to
    work in all apps. Some applications will fail to support the rull range of
    kerning pairs if there are too many; some applications will not support any
    kerning if there are too many pairs; and some older applications may even

    In OpenType fonts, using GPOS instead of kern table kerning, you can employ
    class-based kerning, which can be very handy for large fonts. Some systems
    will decompile GPOS kerning to standard kerning on the fly, which may
    result in subsetting of kerning (Adobe Type Manager and the CFF rasteriser
    in Windows does this for PS-flavour OT fonts, subsetting to Windows CP 1252
    support). The subsetting is necessary because the fully decompiled
    class-based kerning for a font can easily overload many applications (the
    class-based kerning in Adobe's Minion Pro decompiles to approx. 70,000
    pairs). Adobe's latest applications, e.g. InDesign, make direct use of GPOS
    kerning, so can access all the kerning in a font. Hopefully more
    applications and systems will soon follow suit. Windows supports GPOS
    kerning for complex scripts via Uniscribe, but not yet for Latin or other
    'simple' scripts.

    Finally, bear in mind that an excessive number of kerning pairs may
    indicate that your font has fundamental spacing problems. It is often
    possible to reduce the number of kerning pairs by revising the sidebearings
    to produce a better pre-kern fit.

    John Hudson

    Tiro Typeworks
    Vancouver, BC

    It is necessary that by all means and cunning,
    the cursed owners of books should be persuaded
    to make them available to us, either by argument
    or by force. - Michael Apostolis, 1467

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