[NTG-context] parsing custom syntax in lua

Hello, What is the best way to pass verbatim text to lua for processing? I would like to write a lua parser for non-TeX text with a custom syntax (could be something like Markdown for instance). The interface would be \startMyFormat % custom syntax % \stopMyFormat \processMyFormatfile[external file.custom] % alternative The text between \startMyFormat and \stopMyFormat or the text read from the external file should be passed as one utf8-encoded string to a lua function. Any ideas on how to write these macros? On a side note, does anyone know of a quick way to strip diacritical marks from utf8-encoded strings in lua (i.e., transform them to pure ascii)? Thanks, Vianney