When storing word information to the database, indexer converts the words to lower case. Some languages can have special rules for case mapping.
CaseFolding default
With CaseFolding set to default, or when CaseFolding is omitted, mnoGoSearch applies "traditional" lower case mapping rules. U+0049 LATIN CAPITAL LETTER I is mapped to U+0069 LATIN SMALL LETTER I, while U+0130 LATIN CAPITAL LETTER I WITH DOT ABOVE does not change:
I -> i
İ -> İ
CaseFolding turkish
With CaseFolding set to turkish, mnoGoSearch applies special rules when converting to lower case. U+0049 LATIN CAPITAL LETTER I is mapped to U+0131 LATIN SMALL LETTER DOTLESS I, and U+0130 LATIN CAPITAL LETTER I WITH DOT ABOVE is mapped to U+0069 LATIN SMALL LETTER I:
I -> ı
İ -> i
which is suitable for Turkish and
Azerbaijani languages.
CaseFolding turkish2
With CaseFolding set to turkish2, the letters U+0049 LATIN CAPITAL LETTER I, U+0130 LATIN CAPITAL LETTER I WITH DOT ABOVE and U+0131 LATIN SMALL LETTER DOTLESS I are mapped to U+0069 LATIN SMALL LETTER I:
I -> i
İ -> i
ı -> i
which is suitable for indexing Turkish
and English sites in the same database.
Note: indexer.conf and search.htm should set CaseFolding to the same value.