All encoding scenarios include the possibility to provide free text notes. These are encoding in AIXM 5 .1 as Note objects, associated with the TimeSlice that is created for the Event. Each scenario includes further details about the encoding of such Note items, in particular with regard to the values of the propertyName and purpose attributes.
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According to the AIXM Temporality rules, the annotation properties included in a TEMPDELTA TimeSlice completely replace the BASELINE annotations. Therefore, any eventual BASELINE annotation that remains valid during the validity of the TEMPDELTA should be included (copied) in the TEMPDELTA.
Character set
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The Digital NOTAM concept includes the automatic generation of the ICAO text NOTAM from the digital encoding. As explained in the
The NOTAM message needs then to be transmitted on AFTN networks, which only support a limited character set. As the digital encoding in AIXM virtually allows any Unicode character to be used for example in annotations and remarks, there is a potential risk that unsupported characters appear in the NOTAM text. Therefore, it is necessary to limit the character set used in the various fields of a Digital NOTAM encoding to those that can be unambiguously and without information loss be converted into the AFTN supported character set.
According to the Annex 10 to the ICAO Convention (section 4.1.2.1), the following characters are allowed in NOTAM text messages:
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- - (hyphen)
- ? (question mark)
- : (colon)
- ( (open bracket)
- ) (close bracket)
- . (full stop, period, or decimal point)
- , (comma)
- ’ (apostrophe)
- = (double hyphen or equal sign)
- / (oblique)
- + (plus sign)
Characters other than those listed above shall not be used in messages unless absolutely necessary for understanding of the text. When used, they shall be spelled out in full.
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and formatting rules
Annotations shall use the formatting rules and shall be limited to the use of the character set specified in the Character set and text formatting rules.