MODULE CF_CLD
define verb CONVERT
   parameter P1, LABEL=IN, default,
      value (type=$file, default="SYS$INPUT")
   parameter P2, LABEL=OUT, default,
      value (type=$file, default="SYS$OUTPUT")
   qualifier CONVERSION, nonnegatable, placement=global, value
   qualifier SYMBOL, nonnegatable, placement=global, value
   qualifier STRING, nonnegatable, placement=global, value

   disallow (SYMBOL and STRING)
   disallow (SYMBOL and (IN or OUT))
   disallow (STRING and (IN or OUT))