A quick example on what $GPWPL messages are. Keep in mind that the sentence Identifier can also be displayed as $GNWPL. The message is the same but some GNSS receivers use this format.
4917.16,N Latitude of waypoint 12310.64,W Longitude of waypoint 003 Waypoint ID When a route is active, this sentence is sent once for each waypoint in the route, in sequence. When all waypoints have been reported, GPR00 is sent in the next data set. In any group of sentences, only one WPL sentence, or an R00 sentence, will be sent.
1 2 3 4 5 6
1 5128.62 Latitude of nth waypoint on list 2 N North/South 3 00027.58 Longitude of nth waypoint 4 W East/West 5 EGLL Ident of nth waypoint 6 *59 checksum