Thanks, after looking up CompositionExclusions I discovered the rationale: http://unicode.org/reports/tr15/#Primary_Exclusion_List_Table http://unicode.org/rep

Thanks, after looking up CompositionExclusions I discovered the rationale: http://unicode.org/reports/tr15/#Primary_Exclusion_List_Table http://unicode.org/reports/tr15/#Primary_Exclusion_List_Tabl... > When a character with a canonical decomposition is added to Unicode, it must be added to the composition exclusion table if there is at least one character in its decomposition that existed in a previous version of Unicode. If there are no such characters, then it is possible for it to be added or omitted from the composition exclusion table. The choice of whether to do so or not rests upon whether it is generally used in the precomposed form or not.