DUR_MIN
[
VLIB_DURATION_MINUTES:z  {<choice $z>}
]


VLIB_DURATION_MINUTES [
  ( [ one a ] minute ) {return(1)}
  ( [ VSUB_DIGIT_TWO_THRU_NINE:n {return($n)}
      ten {return(10)}
      VSUB_TEEN:t {return($t)}
      VSUB_DECADE:t {return($t)}
      ( VSUB_DECADE:t VSUB_DIGIT_ONE_THRU_NINE:u ) {return(add($t $u))}
    ]
    minutes
  )
  ( ?a half ?an hour ) {return(30)}
  ( [ one an ] hour ) {return(60)}
  ( ?an hour and a half ) {return(90)}
  ( VSUB_DIGIT_TWO_THRU_NINE:h hours ) {return(mul(60 $h))}
  ( VSUB_DIGIT_ONE_THRU_NINE:h and a half hours ) {return(add(mul(60 $h) 30))}
  ( VSUB_DIGIT_TWO_THRU_NINE:h hours ) {return(mul(60 $h))}
  ( [ one an ] hour ?and VSUB_DURATION_MINUTES:m minutes ) {return(add(60 $m))}
  ( VSUB_DIGIT_TWO_THRU_NINE:h hours ?and VSUB_DURATION_MINUTES:m minutes
  ) {return(add(mul($h 60) $m))}

  ; A tenth of an hour is six minutes (for time reporting)
  ( point VSUB_DIGIT_ONE_THRU_NINE:t ?hours ) {return(mul($t 6))}
  ( one tenth ?( of an hour ) ) {return(6)}
  ( VSUB_DIGIT_TWO_THRU_NINE:t tenths ?( of an hour ) ) {return(mul($t 6))}  
  ( VSUB_DIGIT:h point VSUB_DIGIT:t ?hours 
  ) {return(add(mul($h 60) mul($t 6)))}
  ( VSUB_DIGIT_ONE_THRU_NINE:h ?and 
    VSUB_DIGIT_ONE_THRU_NINE:t [ tenth tenths ] ?[ ( of an hour ) hours ]
  ) {return(add(mul($h 60) mul($t 6)))}
]

VSUB_DURATION_MINUTES [
 VSUB_DIGIT_ONE_THRU_NINE:m {return($m)}
   ten {return(10)}
  VSUB_TEEN:t {return($t)}
 VSUB_DURATION_TWENTY_THRU_FIFTY:t {return($t)}  
  ( VSUB_DURATION_TWENTY_THRU_FIFTY:t VSUB_DIGIT_ONE_THRU_NINE:m 
  ) {return(add($t $m))}
]

VSUB_DURATION_TWENTY_THRU_FIFTY [
  twenty {return(20)}
  thirty {return(30)}
  forty {return(40)}
  fifty {return(50)}
]

VSUB_DIGIT_TWO_THRU_NINE[
  two {return(2)}
  three {return(3)}
  four {return(4)}
  five {return(5)}
  six {return(6)}
  seven {return(7)}
  eight {return(8)}
  nine {return(9)}
]

VSUB_DIGIT[
  [ zero oh ] {return(0)}
  VSUB_DIGIT_ONE_THRU_NINE:n {return($n)}
]

VSUB_DIGIT_TWO_THRU_NINE_STRING [
  two {return("2")}
  three {return("3")}
  four {return("4")}
  five {return("5")}
  six {return("6")}
  seven {return("7")}
  eight {return("8")}
  nine {return("9")}
]    

VSUB_DIGIT_ONE_THRU_NINE [
  one {return(1)}
  VSUB_DIGIT_TWO_THRU_NINE:n {return($n)}
]

VSUB_DIGIT_ONE_THRU_NINE_STRING [
  one {return("1")}
  VSUB_DIGIT_TWO_THRU_NINE_STRING:n {return($n)}
]

VSUB_DIGIT_STRING [
  [ zero oh ] {return("0")}
  VSUB_DIGIT_ONE_THRU_NINE_STRING:n {return($n)}
]

VSUB_TEEN_STRING [
  eleven {return("11")}
  twelve {return("12")}
  thirteen {return("13")}
  fourteen {return("14")}
  fifteen {return("15")}
  sixteen {return("16")}
  seventeen {return("17")}
  eighteen {return("18")}
  nineteen {return("19")}
]

VSUB_DECADE_STRING [
  twenty {return("2")}
  thirty {return("3")}
  forty {return("4")}
  fifty {return("5")}
  sixty {return("6")}
  seventy {return("7")}
  eighty {return("8")}
  ninety {return("9")}
]

VSUB_TEEN [
  eleven {return(11)}
  twelve {return(12)}
  thirteen {return(13)}
  fourteen {return(14)}
  fifteen {return(15)}
  sixteen {return(16)}
  seventeen {return(17)}
  eighteen {return(18)}
  nineteen {return(19)}
]

VSUB_DECADE [
  twenty {return(20)}
  thirty {return(30)}
  forty {return(40)}
  fifty {return(50)}
  sixty {return(60)}
  seventy {return(70)}
  eighty {return(80)}
  ninety {return(90)}
]