Re: What is the principle?

From: Peter Kirk (
Date: Fri Mar 26 2004 - 19:27:32 EST

  • Next message: Kenneth Whistler: "Re: What is the principle?"

    On 26/03/2004 14:03, Ernest Cline wrote:

    >It would be nice tho, if there was something like a Private Variation
    I can also see some advantages in this. The current PUA system allows
    private interchange of characters which are completely distinct from
    existing characters. But there are many characters which people might
    like to interchange privately which are in fact variant forms of
    characters already encoded, and which share the identity and all or most
    of the character properties of already encoded characters, differing
    perhaps only in their glyph or in some minor property. If these are
    distinguished from the existing characters only by Private Variation
    Selectors (PVS), which would be default ignorable characters, they can
    retain all of the existing character's properties except for those which
    a private implementation chooses to override.

    If a text encoded in this way is processed or displayed by a regular
    implementation with no understanding of the PVS, it should be processed
    meaningfully except that the property changes will be ignored; and it
    should be displayed meaningfully although with the regular glyph for the
    character. This is a consequence of the PVS being default ignorable.

    I would expect that a rendering engine would be able to ignore the PVS
    when standard fonts are being used; but to render the <character, PVS>
    sequence with the alternate glyph if the font specifies the glyph as a
    kind of ligature for this character sequence.

    I would also expect that the existence of such a feature would be a
    useful way of deflecting a significant number of less well thought out
    new character proposals (including some which are being suggested for

    Peter Kirk (personal) (work)

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