II Morrow Inc. NMC 2001 Operating Manual page 250

Approach Procedures
NAVAID
INW
CSN
TCS
These are most often used for identifying bends in airways that occur at
unnamed positions and other enroute uses. It is unlikely that you will
often see this convention used to name any approach waypoints, but
you will occasionally.
234
DISTANCE
18
106
89
Operations
IDENT
INW18
06CSN
TCS89