sawine@0: constraint       = "constraint" id "(" constraint_term ")"
sawine@0: 
sawine@0: constraint_term  = "time_sep" "at" (string | string_array) 
sawine@0:                      "is" int si_unit 
sawine@0:                      [ "from" int "until" int ]
sawine@0:                      [ "at" "fl" int_array ]
sawine@0: 		   | constraint_term "and" constraint_term
sawine@0: si_unit          = "s" | "min"