As explained in the data encoding section, vertical limits are typically encoded in AIXM as a pair of two attributes:
- a "...Limit" attribute, which includes the value and its unit of measurement (as an "uom" attribute) with the list of values: UomDistanceVerticalType;
- a "...LimitReference" attribute, which indicates what reference system is used for the vertical limit value. It uses the following list of values: CodeVerticalReferenceType.
The following rules shall be applied for the automatic production of the NOTAM text (decoding of the vertical limits):
| "...Limit" Value | "...Limit" @uom | "...LimitReference" | Text to be inserted |
|---|---|---|---|
| GND | any value or NIL | any value or NIL | "SFC" |
| UNL | any value or NIL | any value or NIL | "UNL" |
| FLOOR | any value or NIL | any value or NIL | "Its lower limit" (see Notes below) |
| CEILING | any value or NIL | any value or NIL | "Its upper limit" (see Notes below) |
| XXXXX | FT | SFC | "XXXXXFT AGL" |
| XXXXX | FT | MSL | "XXXXXFT AMSL" |
| XXXXX | FT | W84 | "XXXXXFT above WGS-84 ellipsoid" |
| XXXXX | M | SFC | "XXXXXM AGL" |
| XXXXX | M | MSL | "XXXXXM AMSL" |
| XXXXX | M | W84 | "XXXXXM above WGS-84 ellipsoid" |
| XXX | FL | STD | "FLXXX" |
| XXX | SM | STD | "SMXXX" |
...