section Messages
  description   Messages used for the msg flow
  message 51-O A Submit message normally send from an Application towards an SMSC/Gateway
  message 51-R The response to an 51-O
  message 52-O A deliver message normally send from a SMSC/Gateway towards an Application
  message 52-R The response to an 52-O
  message 53-O A notification message normally send from a SMSC/Gateway towards an Application
  message 53-R The response to an 53-O
  message 60-O Session management (a login message)
  message 60-R The response to an 60-O
  protocol UCP EMI - UCP Protocol description.