It appears that the Unicode Core Specification (version 7.0.0) defines in Table 3-14 what a Final Sigma is. A sigma is final if the previous character is cased and the next is not, ignoring case-ignorable characters completely. To know which characters are cased/case-ignorable, see the properties Cased and Case_Ignorable listed in the file DerivedCoreProperties.txt.
See p.82 (labelled 153) of http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf which says: > C is preceded by a sequence consisting of a cased letter > and then zero or more case-ignorable characters, > and C is not followed by a sequence consisting of zero or > more case-ignorable characters and then a cased letter. > > Before C \p{cased} (\p{case-ignorable})* > After C ! ( (\p{case-ignorable})* \p{cased} ) Regards, Bruno -------------------------------------------------- Subscriptions, Archive, and List information, etc.: http://tug.org/mailman/listinfo/xetex