--- a/yapf/follow_track.cpp
+++ b/yapf/follow_track.cpp
@@ -4,6 +4,12 @@
 #include "yapf.hpp"
 #include "follow_track.hpp"
 
+void FollowTrackInit(FollowTrack_t *This, const Vehicle* v)
+{
+	CFollowTrackWater& F = *(CFollowTrackWater*) This;
+	F.Init(v, NULL);
+}
+
 bool FollowTrackWater(FollowTrack_t *This, TileIndex old_tile, Trackdir old_td)
 {
 	CFollowTrackWater& F = *(CFollowTrackWater*) This;

--- a/yapf/yapf.h
+++ b/yapf/yapf.h
@@ -5,43 +5,103 @@
 
 #include "../debug.h"
 
+/** Finds the best path for given ship.
+	@param v        - the ship that needs to find a path
+	@param tile     - the tile to find the path from (should be next tile the ship is about to enter)
+	@param enterdir - diagonal direction which the ship will enter this new tile from
+	@param tracks   - available tracks on the new tile (to choose from)
+	@return         - the best trackdir for next turn or INVALID_TRACKDIR if the path could not be found
+ */
 Trackdir YapfChooseShipTrack(Vehicle *v, TileIndex tile, DiagDirection enterdir, TrackBits tracks);
+
+/** Finds the best path for given road vehicle.
+	@param v        - the RV that needs to find a path
+	@param tile     - the tile to find the path from (should be next tile the RV is about to enter)
+	@param enterdir - diagonal direction which the RV will enter this new tile from
+	@param tracks   - available tracks on the new tile (to choose from)
+	@return         - the best trackdir for next turn or INVALID_TRACKDIR if the path could not be found
+*/
 Trackdir YapfChooseRoadTrack(Vehicle *v, TileIndex tile, DiagDirection enterdir);
+
+/** Finds the best path for given train.
+	@param v        - the train that needs to find a path
+	@param tile     - the tile to find the path from (should be next tile the train is about to enter)
+	@param enterdir - diagonal direction which the RV will enter this new tile from
+	@param tracks   - available tracks on the new tile (to choose from)
+	@return         - the best trackdir for next turn or INVALID_TRACKDIR if the path could not be found
+*/
 Trackdir YapfChooseRailTrack(Vehicle *v, TileIndex tile, DiagDirection enterdir, TrackdirBits trackdirs);
 
+/** Used by RV multistop feature to find the nearest road stop that has a free slot.
+	@param v      - RV (its current tile will be the origin)
+	@param tile   - destination tile
+	@return       - distance from origin tile to the destination (number of road tiles) or UINT_MAX if path not found
+*/
 uint YapfRoadVehDistanceToTile(const Vehicle* v, TileIndex tile);
 
+/** Used when user sends RV to the nearest depot or if RV needs servicing.
+		Returns the nearest depot (or NULL if depot was not found).
+*/
 Depot* YapfFindNearestRoadDepot(const Vehicle *v);
+
+/** Used when user sends train to the nearest depot or if train needs servicing.
+	@v            - train that needs to go to some depot
+	@max_distance - max distance (number of track tiles) from the current train position
+	                  (used also as optimization - the pathfinder can stop path finding if max_distance
+	                  was reached and no depot was seen)
+	@reverse_penalty - penalty that should be added for the path that requires reversing the train first
+	@depot_tile   - receives the depot tile if depot was found
+	@reversed     - receives true if train needs to reversed first
+	@return       - the true if depot was found.
+*/
 bool YapfFindNearestRailDepotTwoWay(Vehicle *v, int max_distance, int reverse_penalty, TileIndex* depot_tile, bool* reversed);
 
+/** Returns true if it is better to reverse the train before leaving station */
 bool YapfCheckReverseTrain(Vehicle* v);
 
+/** Use this function to notify YAPF that track layout (or signal configuration) has change */
 void YapfNotifyTrackLayoutChange(TileIndex tile, Track track);
 
-
+/** performance measurement helpers */
 void* NpfBeginInterval(void);
 int NpfEndInterval(void* perf);
 
+
 extern int _aystar_stats_open_size;
 extern int _aystar_stats_closed_size;
 
 
+/** Track followers. They should help whenever any new code will need to walk through
+tracks, road or water tiles (pathfinders, signal controllers, vehicle controllers).
+It is an attempt to introduce API that should simplify tasks listed above.
+If you will need to use it:
+	1. allocate/declare FollowTrack_t structure;
+	2. call FollowTrackInit() and provide vehicle (if relevant)
+	3. call one of 6 FollowTrackXxxx() APIs below
+	4. check return value (if true then continue else stop)
+	5. look at FollowTrack_t structure for the result
+	6. optionally repeat steps 3..5
+	7. in case of troubles contact KUDr
+*/
+
 /** Base struct for track followers. */
 typedef struct FollowTrack_t
 {
-	const Vehicle*      m_veh;
-	TileIndex     m_old_tile;
-	Trackdir      m_old_td;
-	TileIndex     m_new_tile;
-	TrackdirBits  m_new_td_bits;
-//	TrackdirBits  m_red_td_bits;
-	DiagDirection m_exitdir;
-	bool          m_is_tunnel;
-	bool          m_is_station;
-	int           m_tiles_skipped;
+	const Vehicle*      m_veh;           ///< moving vehicle
+	TileIndex           m_old_tile;      ///< the origin (vehicle moved from) before move
+	Trackdir            m_old_td;        ///< the trackdir (the vehicle was on) before move
+	TileIndex           m_new_tile;      ///< the new tile (the vehicle has entered)
+	TrackdirBits        m_new_td_bits;   ///< the new set of available trackdirs
+	DiagDirection       m_exitdir;       ///< exit direction (leaving the old tile)
+	bool                m_is_tunnel;     ///< last turn passed tunnel
+	bool                m_is_station;    ///< last turn passed station
+	int                 m_tiles_skipped; ///< number of skipped tunnel or station tiles
 } FollowTrack_t;
 
-/** track followers */
+/** Initializes FollowTrack_t structure */
+void FollowTrackInit(FollowTrack_t *This, const Vehicle* v);
+
+/** Main track follower routines */
 bool FollowTrackWater    (FollowTrack_t *This, TileIndex old_tile, Trackdir old_td);
 bool FollowTrackRoad     (FollowTrack_t *This, TileIndex old_tile, Trackdir old_td);
 bool FollowTrackRail     (FollowTrack_t *This, TileIndex old_tile, Trackdir old_td);
@@ -49,6 +109,7 @@
 bool FollowTrackRoadNo90 (FollowTrack_t *This, TileIndex old_tile, Trackdir old_td);
 bool FollowTrackRailNo90 (FollowTrack_t *This, TileIndex old_tile, Trackdir old_td);
 
+/** Base tile length units */
 enum {
 	YAPF_TILE_LENGTH = 100,
 	YAPF_TILE_CORNER_LENGTH = 71