size-unit glyph -- revisited

I'm now wondering if glyph is the right word that represents what we
have in mind. The sequence of characters "fi", for example, sometimes
are ligated and displayed in one glyph. Whether they are ligated or
not depends on the font and the rendering engine. So the number of
glyph cannot be determined unless we know the environment in which the
string is displayed. On top of that, we most likely don't want to
count "fi" as one size-unit.

I think that what we want to designate using "glyph" is something a
regular user thinks as a "character". In that case, a unit called
"grapheme cluster" Unicode consortium defines [1] may be more
appropriate.

[1] http://www.unicode.org/reports/tr29/tr29-4.html#Grapheme_Cluster_Boundaries

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Shigemichi Yazawa