RE: Prosgegrammeni

From: Philippe Verdy (verdy_p@wanadoo.fr)
Date: Tue May 13 2008 - 12:52:49 CDT

  • Next message: Richard Wordingham: "Re: Prosgegrammeni"

    Russ Stygall wrote:
    > From UnicodeData.txt, 'prosgegrammeni' is equated to 'small letter iota',
    see below.

    Note: Unicode does not "equate" characters, it defines canonical and
    compatibilty equivalence mappings and string canonicalization processes;
    canonical equivalence is based on those mappings, but it does not mean that
    the characters are "equal".

    > 1FBE;GREEK PROSGEGRAMMENI;Ll;0;L;03B9;;;;N;;;0399;;0399
    > 03B9;GREEK SMALL LETTER IOTA;Ll;0;L;;;;;N;;;0399;;0399
    >
    > From the Greek Extended table, see below, the following three characters
    are equated
    > to ALPHA/ETA/OMEGA plus 0345, not plus 1FBE or even 03B9!
    >
    > 1FBC;GREEK CAPITAL LETTER ALPHA WITH PROSGEGRAMMENI;Lt;0;L;0391
    0345;;;;N;;;;1FB3;
    > 1FCC;GREEK CAPITAL LETTER ETA WITH PROSGEGRAMMENI;Lt;0;L;0397
    0345;;;;N;;;;1FC3;
    > 1FFC;GREEK CAPITAL LETTER OMEGA WITH PROSGEGRAMMENI;Lt;0;L;03A9
    0345;;;;N;;;;1FF3;
    >
    > Why is 'iota subscript' (below) used as a substitute for 'iota adscript'
    in the above cases?
    > 0345;COMBINING GREEK YPOGEGRAMMENI;Mn;240;NSM;;;;;N;*;;0399;;0399

    Both U+1FBE and U+03B9 are spacing characters, not combining characters, the
    equivalence between them considers this because U+1FBE is effectively an
    adscript, and definitely not a subscript; the letters with iota subscripts
    are different; Note that the iota adscript is not necessarily below the
    baseline, in fact in many texts it appares on the baseline as well and when
    capitalized it is treated like a standard iota and still becomes a capital
    iota.
     
    U+1FBE is then just a minor graphic variant of a regular iota letter and not
    even guaranteed to be different. On the opposite the combining subscript
    does not change when the text is capitalized.
     
    What can be said is that U+1FBE (the iota adscript) is a compatibility
    character provided only for roundtrip compatibility with other encodings;
    the name may be misleading, for you but "ypogegrammeni" (the combining
    subscript iota) is NOT equivalent to "prosgegrammeni" (the non-combining
    small letter iota that normally follows another letter but may be treated as
    a plain letter itself).
     
    The character names for U+1FBC, U+1FCC and U+1FFC are misleading you, but
    this does not change the encoding and expected properties which look
    correct; the confusion may be the result of the evolution of the Greek
    orthography, where the distinctive subscripts have become adscripts over
    time (that are no longer distinctable from plain letters). But such
    evolution of orthography does not make these iota equivalent: a nchange of
    orthography is still considered as a significant distinction.
     
    > The character 1FBE, in the Greek Extended table of Unicode 5.0, is
    illustrated
    > below the base line, and appears as if it is 0020+0345

    U+1FBE prosgegrammeni is not necessarily below the baseline (this is a
    possible graphic distinction, but it is not mandatory); however, in any
    case, it will never be below another letter or other character.

    It is definitely not equivalent to space+ypogegrammeni, and can appear in
    the middle of words like a normal letter without being considered as a
    symbol and without introducing any word break opportunity.
     
    Philippe.



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