an Additional Service Indication. The second line DD OPKCZQZX is the Address of the message. DD represents the Priority Indicator for the message category(an Urgency Message in this cases). OPKCZQZX is the eight-letter group identifying the addressee. OPKC refers to Karachi/Jinnah Intl, Pakistan. ZQZ refers to a Centre in Charge of Flight Information Region or Upper Flight Information Region'. In other words, the addressee is Karachi Area Control Centre or Karachi Flight Information Centre. The last character X indicates that an explicit identification of the organization or function addressed is not required. So the X is just used to complete the originator address. The third line 120900 OPSTZQZX represents the Origin of the message. 120900 refers to the date-time-group and means the twelfth day of the month at time 09 o'clock UTC. OPSTZQZX is the originator of the message where OPSTZQZX refers to Area Control Centre or Flight Information Centre at Sialkot, Pakistan. The example does not give an explicit MESSAGE TEXT. In reality the contents of the message is included here. The Ending of the message is indicated by NNNN which is the End-of-Message Signal that also has a character pattern that is not found in standard text. The Alignment Functions and letter shift signals mentioned above are not visible in AFTN messages. The message routing is easily automated by general purpose computers. Teleprinter communication with airline operators is sometimes maintained by having a connection to the IATA Type B messaging networks which use a 7 character address. The whole communications system is still rooted in the 'official' nature of radioteletypes. The older tape stations (and perhaps newer ones) also included a bell that could be rung by using a set character code. The purpose of the bell was to allow the sender to alert the receiving operator of a high priority message such as an SS message. It was also possible to insert spacing between bell rings. With care and persistence, one could compose a musical tune to play to far distant stations. Jingle bells was a favourite. A particularly clever 'author' could combine the tune with an image such as a Christmas tree. The skill for this was often learnt on those long night watches when little traffic was in the air. Other airport required reports are also transmitted through the AFTN, on daily and hourly intervals like flight plans, NOTAMs (notices to airmen), and AIRADs (Airfield