# type checking
parameters:
  # + concatenates rules, pad does smart padding
  flight_number:  char(2) + pad(integer(0 .. 9999))
  flight_type:    char(1)
  # variable passed as a parameter to the template
  total_seats:    integer(0 .. :total_seats)
  occupied_seats: integer(0 .. :total_seats)
  # length checks the list, "of string" could be implicit
  passenger_list: list(0 .. :total_seats) of string

# further validation and processing
processing:

  # & references a previously declared field
  # :flights_table could be a list or a hash
  # this might be more appropriate to be on
  # the previous "parameters" instead of here

  - exists &flight_number in :flights_table
  
  # maps the flight type code into a descriptive string
  # using the flight_types hash

  - map &flight_type into :flight_types
  
  # some simple and obvious checks

  - check $occupied_seats < &total_seats
  - check &passenger_list = &occupied_seats

# in-template variable declaration
declare:
  flight_types:
    A: Commercial
    B: Non-Commercial
    C: Cargo