Type Alias AltitudeConstraintDescriptor

AltitudeConstraintDescriptor:
    | "@"
    | "+"
    | "-"
    | "B"
    | "C"
    | "G"
    | "H"
    | "I"
    | "J"
    | "V"
    | "X"
    | "Y"

CIFP altitude constraint descriptor (ARINC 424 field 5.29).

@ - Cross exactly at the altitude.
+ - Cross at or above the altitude.
- - Cross at or below the altitude.
B - Cross between primaryFt and secondaryFt (primaryFt is the higher altitude).
C - Conditional at-or-above (applies above the transition altitude).
G - Glide-slope altitude at the fix.
H - At primaryFt, with secondaryFt describing an associated glide-slope altitude.
I - Glide-slope intercept altitude at the fix.
J - Glide-slope intercept at secondaryFt, cross at or above primaryFt.
V - Minimum altitude step-down published with a vertical angle.
X - At altitude with step-down constraints applied.
Y - At or above altitude with step-down constraints applied.