Editing FM13 Weather Report (section)

== Structure ==
An FM13 BBXX report consists of a strict sequence of data fields, mostly compact numerical codes:

* '''Identifier:''' The report starts with “BBXX” to signal its type.
* '''Callsign:''' A unique ship or station identifier follows.
* '''Date/time group:''' The day and UTC hour (as DDHH), usually giving the hour after the time of observation.
* '''Position:''' Encoded latitude and longitude, with quadrant indicators for hemisphere and longitude direction.
* '''Main meteorological values:''' Atmospheric pressure, wind speed/direction, temperature, cloud cover, sea state, etc., in WMO-prescribed slots.
* '''Slashed/placeholder fields:''' Used if the source does not supply certain data.
* '''End marker:''' The report ends with “=” for positive identification.