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const
  schlssl = '\CLSID\{00B01B2E-B1FE-33A6-AD40-57DE8358DC7D}\InprocServer32\';

function dotnetfx: string;
var
  Reg: TRegistry;
  sl:  TStringList;
  x:   integer;
begin
  Result := '';
  Reg    := TRegistry.Create;
  sl     := TStringList.Create;
  try
    Reg.RootKey := HKEY_CLASSES_ROOT;
    if Reg.OpenKey(schlssl, False) then
    begin
      Reg.GetKeyNames(sl);
      for x := 0 to sl.Count - 1 do
      begin
        Reg.Closekey;
        if Reg.openkey(schlssl + sl[x], False) then
        begin
          if Result <> '' then
            Result := Result + #13#10;
          Result := Result + Reg.ReadString('RuntimeVersion');
        end;
      end;
    end;
  finally
    Reg.CloseKey;
    Reg.Free;
    sl.Free;
  end;
end;