Garmin APOLLO GX65 - Manual (Page 270)

Another type of waypoint which will have a name in
your Apollo GX database, but may or may not appear
on your approach procedure chart is an IAF waypoint
defined as a radial and distance from a VOR. An
example would be the VOR DME RWY 4 approach
to North Bend, Oregon. The IAF at the OTH 164
radial at 14 nm is contained in the Apollo GX
database as D164N (“D” for DME, 164 for 164 radial,
and “N,” the 14th letter of the alphabet, for 14 nm.).
It is also depicted on Jeppesen approach procedure
charts with this name; however, this name is not
found on NOS charts.
9-80
Approach Notes