FontSquirrel's generator will strip out a lot of unneeded characters. By default this means including just the basic Latin subset with the main punctuation glyphs. If you look at the character set for Clear Sans (http://www.fontsquirrel.com/fonts/clear-sans) you will see that it includes Cyrillic and Greek letters, among other things like musical notes and smilie faces, so those can be removed if you don't want them (or included if you do).