mytypes.phonenumber:
  description: my phone number datatype
  properties:
    countrycode:
      type: integer
    areacode:
      type: integer
    number:
      type: integer
      
# define a new datatype that derives from existing type and extends it
mytypes.phonenumber.extended:
  derived_from: mytypes.phonenumber
  description: custom phone number type that extends the basic phonenumber type