sentences:  A single character (other than a Hangul syllable block) that will get replaced by another under normalization can be identified in the Unicode tables for having a non-empty compatibility field but lacking a compatibility tag.The canonical ordering is mainly concerned with the ordering of a sequence of combining characters.For the examples in this section we assume these characters to be diacritics, even though in general some diacritics are not combining characters, and some combining characters are not diacritics.