OTTD's class-specific periodic tile processing routine is called once every +256 ticks for each tile.
 
  
   | Class | Meaning & details of encoding | 
  
   | 0 | Ground | 
  
   |  | 
     m1: owner of the tile (normally 10)m2: see fieldsm3 bits 3..0: see fieldsm4 bits 7..5: type of hedge on the SW border of the tile (1 through 6, or 0=none)m4 bits 4..2: same as 7..5, but for the SE borderm5 bits 7..5: update counter, incremented on every periodic processing for tile types,
         other than 03, 07, 0B, 10 and above.on wraparound, the tile is updated (for fields, the type of fields in m3 is increased, for other types the tile type in m5 is increased).
 For snow and desert, these bits are not used, tile is updated on every periodic processing.
m5 bits 4..2: tile type:
      
       
        | 0 | bare land / grass |  
        | 1 | rough land (density must be 3) |  
        | 2 | rocks (density must be 3) |  
        | 3 | fields (density must be 3) 
          m2: index into the array of industries (farms), INVALID_INDUSTRY (0xFFFF) if farm has been removedm3 bits 3..0: field type (legal values: 0 through 9) |  
        | 4 | snow |  
        | 5 | desert (density must be 1 or 3) | m5 bits 1..0: density:
      
       
        | 0 | bare land |  |  |  | 1/4 snow |  |  
        | 1 | 1/3 grass |  |  |  | 2/4 snow; | 1/2 desert |  
        | 2 | 2/3 grass |  |  |  | 3/4 snow |  |  
        | 3 | full grass; | rough land; | rocks; | fields; | full snow; | full desert | m6 bits 7..6 : Possibility of a bridge above, in the direction specifiedm6 bits 1..0 : Tropic zone definition | 
  
   | 1 | Railway tracks | 
  
   |  | 
     m1: owner of the tilem2: see waypoint and signalsm3 bits 7..4: see signalsm3 bits 3..0 = track type:
      
       
        | 0 | conventional railway |  
        | 1 | electrified railway |  
        | 2 | monorail |  
        | 3 | maglev | m4 bits 7..4: see signalsm4 bits 3..0: Ground type (values with fences are not valid for depots and checkpoints)
      
       
        | 0 | on bare land |  
        | 1 | on grass, no fences |  
        | 2 | fence on the NW side |  
        | 3 | fence on the SE side |  
        | 4 | fences on the NW and SE sides |  
        | 5 | fence on the NE side |  
        | 6 | fence on the SW side |  
        | 7 | fences on the NE and SW sides |  
        | 8 | fence on the E side (track in the W corner) |  
        | 9 | fence on the W side (track in the E corner) |  
        | A | fence on the S side (track in the N corner) |  
        | B | fence on the N side (track in the S corner) |  
        | C | on snow or desert |  
        | D | on grass with fence and shore or water on the free halftile |  
        | E | higher part on foundation with snow, lower without snow | m5 bit 7 clear: railway track
      
       m5 bits 5..0: track layout: bit set = track present:
        
         
          | bit 0: | in the X direction |  
          | bit 1: | in the Y direction |  
          | bit 2: | in the north corner (direction W-E) |  
          | bit 3: | in the south corner (direction W-E) |  
          | bit 4: | in the west corner (direction N-S) |  
          | bit 5: | in the east corner (direction N-S) | m5 bit 6 set = with signals:There are at most 4 signals on a tile. The signals 0..3 belong to the directions:
 
         
          |  | Track 0 (X) | Track 1 (Y) | Track 2 (north) | Track 3 (south) | Track 4 (west) | Track 5 (east) |  
          | Signal 0 |  |  |  | west |  | south |  
          | Signal 1 |  |  |  | east |  | north |  
          | Signal 2 | south-west | north-west | west |  | south |  |  
          | Signal 3 | north-east | south-east | east |  | north |  |  
         m2 bit 7: Signal 0 and 1: set = semaphore signals, clear = light signalsm2 bit 3: Signal 2 and 3: set = semaphore signals, clear = light signalsm2 bits 6..4: type of signal 0 and 1 (same values as m2 bits 2..0)m2 bits 2..0: type of signal 2 and 3
          
           
            | 000: | normal signals |  
            | 001: | pre-signals |  
            | 010: | exit-signals |  
            | 011: | combo-signals |  
            | 100: | pbs signals |  
            | 101: | no-entry signals | m3 bits 7..4: bit set = signal 3..0 presentm4 bits 7..4: bit clear = signal 3..0 shows redm2 bits 8..10: track reserved for pbs
         
          
            | 0 | not reserved |  
            | 1 | X direction |  
            | 2 | Y direction |  
            | 3 | north corner (W-E) |  
            | 4 | south corner (W-E) |  
            | 5 | west corner (N-S) |  
            | 6 | east corner (N-S) | m2 bit 11: opposite track is reserved, toom5 bit 7 set, bit 6 clear: checkpoint
      
       m2: index into the array of waypoints.m5 bit 0:
        
         
          | 0 | in X direction |  
          | 1 | in Y direction | m5 bit 4: pbs reservation statem5 bit 7 set, bit 6 set: railway depot
      
       m5 bits 1..0: exit towards
        
       m5 bit 4: pbs reservation statem6 bits 7..6 : Possibility of a bridge above, in the direction specifiedm6 bits 1..0 : Tropic zone definition | 
  
   | 2 | Roads | 
  
   |  | 
     m2: Index into the array of towns (owning town for town roads; closest town otherwise, INVALID_TOWN if there is no town or we are creating a town)m3 bit 7 set = on snow or desertm7 bits 7..5: present road types
      
       
        | bit 0 | normal road |  
        | bit 1 | tram |  
        | bit 2 | reserved | m5 bits 7 clear: road or level-crossing
      
       m3 bits 6..4:
        
         
          | 0 | on bare land |  
          | 1 | on grass |  
          | 2 | paved |  
          | 3 | with streetlights |  
          | 5 | tree-lined |  
          | 6 | on grass with road works |  
          | 7 | paved with road works | m5 bits 3..0: owner of road type 1 (tram); OWNER_NONE (10) is stored as OWNER_TOWN (0F)
       m7 bits 4..0: owner of road type 2 (reserved)
       m5 bit 6 clear: road
        
         m1: owner of the road type 0 (normal road)m3 bits 3..0: counter for the roadworksm4 bits 3..0: road layout road type 0 (normal road): bit set = road piece present:
          
           
            | bit 0: | NW piece |  
            | bit 1: | SW piece |  
            | bit 2: | SE piece |  
            | bit 3: | NE piece | m4 bits 7..4: road layout road type 1 (tram)m6 bits 5..2: road layout road type 2 (reserved)m5 bits 5..4: bits to disallow vehicles to go a specific direction
          
           
            | bit 0: | set = disallow driving in south-west or south-east direction |  
            | bit 1: | set = disallow driving in north-west or north-east direction | m5 bit 6 set: level crossing
        
         m1: owner of the railway trackm3 bits 3..0: railway track typem4 bit 6: direction
          
           
            | 0 | road in the X direction, rail in Y |  
            | 1 | road in the Y direction, rail in X | m4 bit 5: set if crossing lights are onm4 bits 4..0: owner of the road type 0 (normal road)m5 bit 4: pbs reservation statem5 bit 7 set, bit 6 clear: road depot
      
       m1: owner of the depotm5 bits 3..0: exit towards:
        
       m6 bits 7..6 : Possibility of a bridge above, in the direction specifiedm6 bits 1..0 : Tropic zone definition | 
  
   | 3 | Town building | 
  
   |  | 
     Newhouses is the name englobing a newGRF feature developped by TTDPatch devs (mainly Csaboka).m1 : Random bits (newhouses) m2 : index into the array of townsm3 bit 7 :
      
        set : House is complete
        
         m5 : Age of house in years, clamped at 255 clear : House is in construction
        
         m5 bits 7..5 : freem5 bits 4..3 : construction stagem5 bits 2..0 : construction counterm3 bit 6 : bit 8 of house type (m4), allowing 512 different types.m3 bit 5 : bit 6 of current animation frame (see m6)m3 bits 4..0 : triggers activated (newhouses)m4 : town building type (with m3[6] bit)m5 : see m3 bit 7m6 :
      
       If newhouses is activated
        
         bits 7..2 : Current animation frame (bits 5..0); bit 6 in m3Standard behaviour
        
         bits 7..2 : lift position (for houses type 04 and 05)bits 1..0 : tropic zone specifierm7 :
      
       If newhouses is activated
        
         Periodic processing time remainingStandard behaviour (only for houses type 04 and 05)
        
         bits 7..4 : freebits 3..1 : lift destination.  Values can be 0..6, except 1.So the building has 6 effective floors. This is due to the fact that the first floor is 2 'normal' floors high.
 One 'normal' floor has a height of 6 lift positions.
bit 0 : Lift has destination when set It allows the replacement of the properties as well as the graphics of houses in the game.
 To distinguish between the standard behaviour and the newGRF one, HouseID (m4 + m3[6]) is tested for anything above 110.
 110 is the count of standard houses. So above 110 means there is a new definition of at least one house
 | 
  
   | 4 | Trees | 
  
   |  | 
     m1: owner (normally 10)m2 bits 7..6: ground density
     m2 bits 5..4: ground
      
       
        | 0 | on grass |  
        | 1 | on rough land (density must be 3) |  
        | 2 | on snow or desert |  
        | 3 | on shore (density must be 3) | m2 bits 3..0: update counter, incremented on every periodic processing.on wraparound the growth status is updated (or, if it's 3, a random action is taken)
m3 bits 7..0: type of trees:
      
       Note: the actually displayed set of trees depends on both type and number of trees
        | 00..0B | temperate climate trees |  
        | 0C..13 | sub-arctic climate trees |  
        | 14..1A | rainforest trees |  
        | 1B | cactus plants |  
        | 1C..1F | sub-tropical climate, non-rainforest, non-desert trees |  
        | 20..28 | toyland trees | m4 bits 7..5: type of hedge on the SW border of the tile (1 through 6, or 0=none)m4 bits 4..2: type of hedge on the SE border of the tile (1 through 6, or 0=none)m5 bits 7..6: number of trees minus onem5 bits 2..0: growth status:
      
       
        | 0..2 | one of trees is growing |  
        | 3 | all trees are fully grown |  
        | 4..6 | one of trees is withering | m6 bits 1..0 : Tropic zone definition | 
  
   | 5 | Station tiles | 
  
   |  | 
     m1: owner of the stationm2: index into the array of stationsm3 bits 7..4: persistent random data for newstationsm3 bits 3..0: track type for railway stationsm3 bits 2..0: present road types for road stopsm3 bits 1..0: water class for buoys and water part of docksm4: custom station id; 0 means standard graphicsm5: graphics index (range from 0..255 for each station type):
      
       
        | 00..07 | railway station 
          
           | 00..01 | open platform |  
           | 02..03 | open platform with station building |  
           | 04....07 | roofed platform |  
           | bit 0: clear = in X direction, set = in Y direction |  |  
        | 00..8F | all airports |  
        | 00..05 | road stops: 
          
           | 00 | exit towards NE |  
           | 01 | exit towards SE |  
           | 02 | exit towards SW |  
           | 03 | exit towards NW |  
           | 04 | drive through X |  
           | 05 | drive through Y |  |  
        | 00..05 | ship dock 
          
           | 00 | SW coast part |  
           | 01 | NW coast part |  
           | 02 | NE coast part |  
           | 03 | SE coast part |  
           | 04 | X direction water part |  
           | 05 | Y direction water part |  | m6 bits 5..3: the station type (rail, airport, truck, bus, oilrig, dock, buoy)m6 bit 2: 1 when a drive through road stop is built over a town owned road, otherwise 0m6 bit 2: pbs reservation state for railway stationsm6 bits 1..0 : Tropic zone definitionm7: animation frame | 
  
   | 6 | Water | 
  
   |  | 
     m1: owner (for sea, rivers, and coasts normally 11)m3 bits 1..0 : Water class (sea, canal or river)
     m4: Random data for canal or river tilesm5: tile type:
      
       
        | 00 | water, canal or river |  
        | 01 | coast or riverbank |  
        | 10..1B | canal locks 
          
           | 10 | middle part, (SW-NE direction) |  
           | 11 | middle part, (NW-SE direction) |  
           | 12 | middle part, (NE-SW direction) |  
           | 13 | middle part, (SE-NW direction) |  
           | 14 | lower part, (SW-NE direction) |  
           | 15 | lower part, (NW-SE direction) |  
           | 16 | lower part, (NE-SW direction) |  
           | 17 | lower part, (SE-NW direction) |  
           | 18 | upper part, (SW-NE direction) |  
           | 19 | upper part, (NW-SE direction) |  
           | 1A | upper part, (NE-SW direction) |  
           | 1B | upper part, (SE-NW direction) |  |  
        | 80..83 | ship depots 
          
           | 80 | ship depot, NE part (X direction) |  
           | 81 | ship depot, SW part (X direction) |  
           | 82 | ship depot, NW part (Y direction) |  
           | 83 | ship depot, SE part (Y direction) |  | m6 bits 7..6 : Possibility of a bridge above, in the direction specifiedm6 bits 1..0 : Tropic zone definition | 
  
   | 7 | Void | 
  
   |  | Tiles of this class form an invisible, one tile wide border at the south (bottom) edges of the map, so as to protect several algorithms from the consequences of a wraparound at the edges.
 | 
  
   | 8 | Industry tile | 
  
   |  | 
     m1 bit 7: clear = under construction
      
       m1 bits 6..5 : Water class (sea, canal, river or land)
       m1 bits 3..2: construction counter, for buildings under construction incremented on every periodic tile processingm1 bits 1..0: stage of construction (3 = completed), incremented when the construction counter wraps aroundthe meaning is different for some animated tiles which are never under construction (types 01, 1E..20, 30, 58; see above)
m2: index into the array of industriesm3: animation statem4: animation loopm5: type (plus m6 bit 2):(note: this is not the same as the industry type, which is stored in the array of industries)
 
       
        | 00..06 | coal mine 
          
           | 00 | wheel tower when not animated |  
           | 01 | wheel tower when animated animation state in m3 bits 5..0; m3 bit 6 set = sound already generated
 |  |  
        | 07..0A | power station 
          
           | 08 | chimney |  
           | 0A | transformer; animation progress in m3(valid range 0..7) |  |  
        | 0B..0F | sawmill |  
        | 10..11 | forest |  
        | 12..17 | oil refinery |  
        | 18..1C | oil rig |  
        | 1D..20 | oil wells 
          
           | 1D | not animated |  
           | 1E..20 | various stages of animation; progress of animation in m3 |  |  
        | 21..26 | farm |  
        | 27..2A | factory (temperate climate) |  
        | 2B..2E | printing works |  
        | 2F..33 | copper ore mine 
          
           | 2F | wheel tower when not animated |  
           | 30 | wheel tower when animated; animation state in m3 bits 5..0; m3 bit 6 set = sound already generated |  
           | 31 | chimney |  |  
        | 34..39 | steel mill |  
        | 3A..3B | bank (temperate climate) |  
        | 3C..3F | food processing plant |  
        | 40..47 | paper mill |  
        | 48..58 | gold mine 
          
           | 4F | wheel tower when not animated |  
           | 58 | wheel tower when animated; animation state in m3 bits 5..0; m3 bit 6 set = sound already generated |  |  
        | 59..5A | bank (sub-arctic or sub-tropical climate) |  
        | 5B..63 | diamond mine |  
        | 64..73 | iron ore mine |  
        | 74 | fruit plantation |  
        | 75 | rubber plantation |  
        | 76..77 | water supply |  
        | 78 | water tower |  
        | 79..7C | factory (sub-tropical climate) |  
        | 7D..80 | lumber mill |  
        | 81..82 | candyfloss forest 
          
           | 82 | candyfloss 'trees' cut down |  |  
        | 83..86 | sweet factory |  
        | 87..88 | battery farm |  
        | 89 | cola wells |  
        | 8A..8D | toy shop |  
        | 8E..93 | toy factory 
          
           | 8F | Animated part; animation state in m3 (valid range 00..31) Tile animation is started (m4 zeroed) on the periodic processing.
 While the animation is in progress, m4 holds the number
                        of animation cycles that have already taken place.
 when this number reaches 8 the animation is stopped.
 |  |  
        | 94..9B | plastic fountains (various stages of cyclic animation) |  
        | 9C..9F | fizzy drink factory |  
        | A0..A3 | bubble generator 
          
           | A1 | generators |  
           | A2 | bubble capture facility; animation state in m3 (valid range 00..27) |  |  
        | A4..A6 | toffee quarry 
          
           | A5 | animated part; animation state in m3 (valid range 00..45) |  |  
        | A7..AE | sugar mine 
          
           | AE | animated part; animation state in m3 (valid range 00..5F) |  |  
        | AF..1FF | NewGRF industries industry | m6 bits 5..3: random triggers (NewGRF)m6 bit 2: bit 8 of type (see m5)m6 bits 1..0 : Tropic zone definitionm7: random bits (NewGRF) | 
  
   | 9 | Tunnel / bridge | 
  
   |  | 
     m1: ownerm2 bits 7..4: see bridge rampm3 bits 3..0: track type for railwaym3 bits 2..0: present road types for roadm4 bit 7 set = on snow or desertm5 bit 4: pbs reservation state for railwaym5 bits 7 clear: tunnel entrance/exitm5 bit 7 set: bridge ramp
      
       m2 bits 7..4: bridge type:
        
         
          | Type | Max. speed (mph) | Description |  
          | 0 | 20 | wooden |  
          | 1 | 30 | concrete |  
          | 2 | 40 | girder, steel |  
          | 3 | 50 | suspension, concrete |  
          | 4 | 60 | suspension, steel |  
          | 5 | 70 | suspension, steel |  
          | 6 | 100 | cantilever, steel |  
          | 7 | 130 | cantilever, steel |  
          | 8 | 150 | cantilever, steel |  
          | 9 | 160 | girder, steel |  
          | A | 200 | tubular, steel |  
          | B | 320 | tubular, steel |  
          | C | 380 | tubular, silicon | m5 bits 3..2: transport type
      
       
        | 0 | railway |  
        | 1 | road |  
        | 2 | water |  m5 bits 1..0: direction onto the bridge / out of the tunnel
      
     m6 bits 7..6 : Possibility of a bridge above, in the direction specifiedm6 bits 1..0 : Tropic zone definition
   | A | Unmovables |  
   |  | 
     m1: owner of the object (for lighthouses and transmitters normally 10)m2: see company statue
     m5: tile type:
      
       
        | 00 | transmitter |  
        | 01 | lighthouse |  
        | 02 | company statue 
          m2: TownID on which the statue is built in |  
        | 03 | company-owned land |  
        | 80..93 | company headquarters (5 sets of 4 tiles each, updated quarterly depending on the company performance) | m6 bits 7..6 : Possibility of a bridge above, in the direction specifiedm6 bits 1..0 : Tropic zone definition |  
   | Classes B through F are reserved. The presence
      of a tile in one of the reserved classes will crash OTTD. |  Original Copyright © 2003 by Marcin Grzegorczyk for TTDLX.
 Transport Tycoon and Transport Tycoon Deluxe are Copyright © by Chris Sawyer.
 All the other trademarks are the property of their respective owners.
 
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