Here is Unicode Technical Standard #18 written by Mark Davis himself
that gives clues to what Unicode means by "characters":
http://unicode.org/reports/tr18/ Look for:
"One or more Unicode characters may make up what the user thinks of
as a character. To avoid ambiguity with the computer use of the term
character, this is called a grapheme cluster. For example, "G" +
acute-accent is a grapheme cluster: it is thought of as a single
character by users, yet is actually represented by two Unicode
characters."
Regards, Mete