II Morrow Inc. NMC 2001 - Page 250

NAVAID DISTANCE IDENT
INW 18 INW18
CSN 106 06CSN
TCS 89 TCS89
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.
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Approach Procedures Operations