The language collation (or sorting) DLL, libqdb_cldr.so, implements the Unicode Collation Algorithm. This algorithm is a multi-level comparison algorithm, where each character has a number of weights.
These character weights typically correspond to the base character, accents, case, and punctuation. The primary weight has the most relevance, while lower-level weights provide a tie-breaking role; that is, they determine sort order when two or more different elements are assigned the same primary weight.
For example, depending on specific language, locale and even institutional conventions, the characters “a” and “á”, and “A” and “Á” might all be assigned the same primary weight, but require differentiation at the secondary and tertiary levels respectively.
For more information about the Unicode Collation Algorithm, see www.unicode.org/reports/tr10/.