Source: Mark Davis
Subject: Feedback on #44
In UAX #44 we find the following text:
In contrast, some normalization-related Unicode character properties are not recommended for exposure in a public library API. Notably, these include Decomposition_Mapping, Composition_Exclusion, and the derived Full_Composition_Exclusion. These properties are only used internally in a conformant implementation of the Unicode Normalization Algorithm. Exposing them in a public API can lead to confusion by users of the API. In particular, Decomposition_Mapping is very easy to misinterpret as designating the decomposition of a character, also known as the character's full decomposition. See Definitions D62 and D64 in Section 3.7, Decomposition in [Unicode].