This sets up the SWR extension and associates it with notepad 

   {
    regKey->RootKey = HKEY_CLASSES_ROOT;
    regKey->OpenKey("\\txtfile\\shell\\open\\command",true);
    TXTLocation = regKey->ReadString("");
    regKey->OpenKey("\\.SWR",true);
    regKey->WriteString("","SWR_auto_file");
    regKey->OpenKey("\\SWR_auto_file",true);
    regKey->WriteString("", "SWR ReportFile");
    regKey->OpenKey("\\SWR_auto_file\\DefaultIcon",true);
    regKey->WriteString("",(ProgramPath + "ReportFile.ico,0"));
    regKey->OpenKey("\\SWR_auto_file\\shell\\open\\command",true);
    regKey->WriteString("", TXTLocation);
    }

This sets up the RUS extension and associates it with the current program as well as ensuring the program auto-opens when the .RUS file is double-clicked.

String ProgExe = ExtractFilePath(Application->ExeName);
String ProgramPath = ProgExe;
ProgExe = ProgExe + ExtractFileName(Application->ExeName) + " %1";
TRegistry* regKey = new TRegistry();
regKey->RootKey = HKEY_CLASSES_ROOT;
// register icon
if(!regKey->ReadString("\\RUS_auto_file\\shell\\open\\command").Pos('1'));
{
    regKey->OpenKey("\\.RUS",true);
    regKey->WriteString("","RUS_auto_file");
    regKey->OpenKey("\\RUS_auto_file",true);
    regKey->OpenKey("\\RUS_auto_file",true);
    regKey->WriteString("", "RUS Russian Text File");
    regKey->OpenKey("\\RUS_auto_file\\DefaultIcon",true);
    regKey->WriteString("",(ProgramPath) + "RusIcon.ico,0");
    regKey->OpenKey("\\RUS_auto_file\\shell\\open\\command",true);
    regKey->WriteString("", ProgExe);
}
delete regKey;