${o}'); below to indicate the path to the sdml2txt converter like this: ContentRegFSConverter('sdml', 'sd', '/sdml2txt < ${i} > ${o}'); */ define(SDML_VERSION, '1.0'); ContentRegisterType('sdml', 'text/plain', 'sdml', null, true); ContentRegisterType('sd', 'text/plain', 'txt', null, true); ContentRegFSConverter('sdml', 'sd', 'sdml2txt < ${i} > ${o}'); ContentRegConverter('sd', 'safe', "Sdml_sd2safe"); function Sdml_sd2safe($cp, $cnv, $intype, $outtype, $args, $data) { return "[@$data@]"; }