The coding and decoding rules for Digital NOTAM are presented under predefined scenarios. Scenarios correspond to common situations that occur in the aeronautical information domain and which are usually notified by NOTAM, such as runway closures, airspace activation, etc. The advantage of defining scenarios is that it enables capturing specific coding rules, which can be used for verifying the correctness and the completeness of the coding. This also facilitates that data downstream, for example by enabling to sort the events by the subject affected and by its condition. This can also facilitate the detection of data which is relevant for specific use cases, such as detecting runway events and temporary obstacles that are relevant for aircraft take-off performance calculation.
Each event scenario contains a description of the applicable rules for encoding the data using the AIXM model and also the rules that may be applied in order to automatically generate the ICAO compliant text NOTAM.
Each Digital NOTAM coding scenario has a unique identifier that is intended to be human readable. It is composed of two groups of letters:
In an AIXM file that contains Digital NOTAM data, this identifier shall be put in the "scenario" attribute of the Event feature.In addition, the version of the Digital NOTAM Specification according to which the encoding was done shall also be specified.
The data usually provided by the data originators for each event category is presented in the form of an "input" diagram, using EBNF (Extended Backus Naur Form). The same notation is used for the production rule for the E item of the NOTAM text. The document includes graphical representations of the EBNF rules and some specific graphical elements, as described below.