As explained in the data encoding section, vertical limits are typically encoded in AIXM as a pair of two attributes:

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

"SFC"
UNL

"UNL"
FLOOR

"Its lower limit" (see Notes below)
CEILING

"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 MSFC"XXXXXM AGL"
XXXXX MMSL"XXXXXM AMSL"
XXXXX MW84"XXXXXM above WGS-84 ellipsoid"
XXXFT STD"FLXXX"
XXXSMSTD"SMXXX"


Notes: