[NTG-context] UTF conversion via Lua

Hello, I have many files with ASCII encoding; this encoding must be kept as these files are processed also by another program. When I work with them in ConTeXt, I need to convert them to UTF. Does Lua (in ConTeXt scope) offer a transformation function or a table of chars [ASCII-code] -> [UTF-code] or anything to provide the conversion? Something like: \startluacode local str = loadFile("a.txt") -- ASCII coded str = context.ACSII2UTF(str) -- Or something like this \stopluacode Best regards, Lukas -- Ing. Lukáš Procházka [mailto:LPr@pontex.cz] Pontex s. r. o. [mailto:pontex@pontex.cz] [http://www.pontex.cz] Bezová 1658 147 14 Praha 4 Tel: +420 244 062 238 Fax: +420 244 461 038