NML:Industries

NewGRF Meta Language

Preface

Getting started

Graphics files

Blocks

Units

Expressions

Elementary values

Builtin functions

Language files

Lists of props, vars and CBs

Warnings

Additional references

NewGRF compatibility

Deprecated syntax

Changes from NML 0.2 to 0.3

Changes from NML 0.3 to 0.4

Changes from NML 0.4 to 0.5

Vehicles, Stations, Canals, Bridges, Towns, Houses, Industries (Tiles), Cargos, Airports+Tiles, Objects, Railtypes, Roadtypes, Tramtypes, Terrain

NML Tutorial

Props, Vars and CBs

General

• variables

Vehicles

• common props | vars | CBs
• train | roadveh | ship | aircr props

Stations

• properties | variables | callbacks

Canals

• properties | variables | callbacks

Bridges

• properties | variables | callbacks

Towns

Houses

• properties | variables | callbacks

Industries

• common variables
• industry props | vars | CBs
• tile props | vars | CBs

Cargos

• properties | variables | callbacks

Airports

• airport props | vars | CBs
• tile props | vars | CBs

Objects

• properties | variables | callbacks

Railtypes

• properties | variables | callbacks

Roadtypes

• properties | variables | callbacks

Tramtypes

• properties | variables | callbacks

This page contains information on industry properties, variables and callbacks. Industry tiles are closely related.

Industry ID allocation

Industry IDs are local to the NewGRF, you are free to choose any ID in the 0..127-range. You should start your item definition with the 'substitute'-property, which allocates a new industry. The value of this property should be the ID of a default industry, which will be used instead of your item if it is not available for whatever reason (for example, missing NewGRF).

Furthermore, you can set the 'override'-property, which will cause the existing industry to be replaced with your item. You should use this if you are for example defining a coal mine which changes production more dynamically. If your type is not a direct replacement of an existing item, don't set this property.

Industry properties

Industry properties. Default industry type numbers can be found at default industries.

property	value range	comment
substitute	industry type	Number of the original industry type that replaces this one, should it not be available for some reason (e.g. missing NewGRF). This property must be set first, before any other properties or graphics. All properties of the old type are copied to your new industry.
override	industry type	Number of the original industry type overridden. This will cause other grfs / industries to consider your industry type the same as the old type. Only set this property if your type is (more or less) the same as the old type.
layouts	Array of tilelayouts	See Tilelayout syntax.
life_type	One of IND_LIFE_TYPE_XXX, XXX = BLACK_HOLE | EXTRACTIVE | ORGANIC | PROCESSING	The generic type of industry. This determines the production changes that occur by default (when not using the callback). Examples are respectively power plants, coal mines, forests en steel mills.
closure_msg	string	Message displayed when the industry announces closure. Use a custom string or one of the default TTD strings.
prod_increase_msg	string	Message displayed when industry increases production. Use a custom string or one of the default TTD strings.
prod_decrease_msg	string	Message displayed when industry decreases production. Use a custom string or one of the default TTD strings.
fund_cost_multiplier	0..255	Fund cost multiplier. Note that in OpenTTD the unmodified base cost is 8x higher for building (not prospecting) raw (=extractive / organic, see life_type) industries.
cargo_types	array of accept_cargo(input, outputs...) and produce_cargo(output, level) expressions	NML 0.5 1.9 Types of cargo accepted and produced by the industry, and their production levels and production multipliers. See cargo types array below.
prod_cargo_types	array of up to 2 ints	NML 0.4 Types of cargo produced. Use the cargotype(<label>) built-in function to specify a label from the cargotable. NML 0.5 Removed, use cargo_types instead.
accept_cargo_types	array of up to 3 ints	NML 0.4 Types of cargo accepted. Use the cargotype(<label>) built-in function to specify a label from the cargotable. NML 0.5 Removed, use cargo_types instead.
prod_multiplier	array of up to 2 ints (0..255)	NML 0.4 Amount of each output cargo to produce every 256 ticks (8 or 9 times a month) NML 0.5 Removed, use cargo_types instead.
min_cargo_distr	0..255	Minimal amount of cargo before transporting to stations.
random_sound_effects	array of ints	Sound effect numbers that are played some times.
conflicting_ind_types	array of up to 3x industry_type(IND_TYPE_OLD | IND_TYPE_NEW, id)	Three industry types that should not be nearby. Use the builtin function industry_type(..) to define either an old industry (using the global ID) or a new industry from your grf (using the grf-local ID).
prob_random	0..255	(up to NML v5796-418, use prob_map_gen otherwise) Probability of occurring while generating initial industries. If the random game probability value is nonzero and IND_FLAG_DO_NOT_FORCE_INSTANCE_AT_MAP_GENERATION is not set, at least one instance of this type is guaranteed to appear on the map.
prob_map_gen	0..255	(NML v5796-418 or newer) Probability of occurring while generating initial industries. If the random game probability value is nonzero and IND_FLAG_DO_NOT_FORCE_INSTANCE_AT_MAP_GENERATION is not set, at least one instance of this type is guaranteed to appear on the map.
prob_in_game	0..255	Probability of occurring while creating industries during the game.
map_colour	0..255	Colour index from the DOS palette to use on the minimap for this industry.
spec_flags	bitmask(flags)	for flag values see Industry special flags
new_ind_msg	string	Message displayed when industry gets built during game play.
input_multiplier_1	array of up to 2 floats (0..255)	NML 0.4 Output cargo multiplication factors for getting a unit of the first accepted cargo. NML 0.5 Removed, use cargo_types instead.
input_multiplier_2	array of up to 2 floats (0..255)	NML 0.4 Output cargo multiplication factors for getting a unit of the second accepted cargo. NML 0.5 Removed, use cargo_types instead.
input_multiplier_3	array of up to 2 floats (0..255)	NML 0.4 Output cargo multiplication factors for getting a unit of the third accepted cargo. NML 0.5 Removed, use cargo_types instead.
name	string	Name of the industry, use a custom string or one of the default TTD strings.
prospect_chance	0 .. 1 (float)	Chance of successful prospecting.
callback_flags	bitmask(flags)	Do not set this, unless you use old-style callbacks.
remove_cost_multiplier	int	Cost multiplier for removing the industry (currently only possible with magic bulldozer).
nearby_station_name	string	Default name for a nearby station. To follow the "<Town Name> <Industry Name>" convention, the string should include a "{STRING}" at the position the town name shall be inserted. For example: STR_HARBOR_NEARBY_NAME :{STRING} water side

Cargo types array

The cargo_types property takes an array of accept_cargo and produce_cargo expressions. This array is used to define which cargo types the industry accepts, which it produces, and how much cargo is produced on production ticks and on delivery. All cargo types the industry handles must be mentioned in its cargo_types property even when they are handled by production callbacks.

The following is an example of a cargo_types property:

cargo_types: [
  produce_cargo("GOOD", 4),
  accept_cargo("PASS"),
  produce_cargo("PASS", 0),
  accept_cargo("IORE", produce_cargo("STEL", 1), produce_cargo("SLAG", 0.25))
]

The above example has four items in its cargo_types array, two produce_cargo expressions and two accept_cargo expressions.

1. produce_cargo("GOOD", 4) specifies the industry produces GOOD at a rate of 4 every production tick (256 game ticks), this production rate is scaled by the industry's production level.
2. accept_cargo("PASS") specifies the industry accepts PASS as a "black hole", that is no cargo is produced when PASS is delivered. If you have a production callback that consumes a cargo you will also need to specify that cargo in this way.
3. produce_cargo("PASS", 0) specifies the industry produces PASS but not on the production ticks as usual. Specifying a production rate of zero is only useful for cargo types you produce via a production callback.
4. accept_cargo("IORE", produce_cargo(...), ...) specifies the industry produces the listed cargo types every time IORE is delivered. In the example above, delivering one IORE will result in one STEL produced and no SLAG produced (because 1*0.25 is zero after rounding down), and delivering 4 IORE will result in 4 STEL and 1 SLAG produced.

At most 16 different cargo labels may appear in accept_cargo and at most 16 different cargo labels in produce_cargo, for a single industry. The same cargo label can be used in as many accept_cargo or produce_cargo as necessary.

More complex production rules can be set up via the production callbacks, see callbacks below.

Industry special flags

flag	meaning
IND_FLAG_PLANT_FIELDS_PERIODICALLY	The industry periodically plants fields around itself (temperate and arctic farms)
IND_FLAG_CUT_TREES	The industry cuts trees around itself and produces its first output cargo from them (lumber mill)
IND_FLAG_BUILT_ON_WATER	The industry is built on water (oil rig)
IND_FLAG_ONLY_IN_LARGE_TOWNS	The industry can only be built in towns (i.e. it has to replace houses) with population larger than 1200 (temperate bank)
IND_FLAG_ONLY_IN_TOWNS	The industry can only be built in towns (i.e. it has to replace houses) (arctic and tropic banks, water tower)
IND_FLAG_BUILT_NEAR_TOWN	The industry is always built near towns (i.e. near town sign; additionally the industry is allowed to replace houses) (toy shop)
IND_FLAG_PLANT_FIELDS_WHEN_BUILT	Fields are planted around the industry when it's built (all farms)
IND_FLAG_NO_PRODUCTION_INCREASE	The industry cannot increase its production on the temperate climate (oil wells)
IND_FLAG_BUILT_ONLY_BEFORE_1950	The industry is built only before 1950 (oil wells)
IND_FLAG_BUILT_ONLY_AFTER_1960	The industry is built only after 1960 (oil rig)
IND_FLAG_AI_CREATES_AIR_AND_SHIP_ROUTES	AI players will attempt to establish air and ship routes going to this industry (oil rig)
IND_FLAG_MILITARY_AIRPLANE_CAN_EXPLODE	The industry can be exploded by a military airplane (oil refinery)
IND_FLAG_MILITARY_HELICOPTER_CAN_EXPLODE	The industry can be exploded by a military helicopter (factory)
IND_FLAG_CAN_CAUSE_SUBSIDENCE	The industry can cause a subsidence (coal mine)
IND_FLAG_AUTOMATIC_PRODUCTION_MULTIPLIER	Automatic production multiplier handing (No industry has this bit set by default.).
IND_FLAG_RANDOM_BITS_IN_PRODUCTION_CALLBACK	The production callback needs random bits in var. 10 (No industry has this bit set by default.)
IND_FLAG_DO_NOT_FORCE_INSTANCE_AT_MAP_GENERATION	Do not force one instance of this type to appear during initial map generation (No industry has this bit set by default.)
IND_FLAG_ALLOW_CLOSING_LAST_INSTANCE	Allow closing down the last instance of this type (No industry has this bit set by default.)
IND_FLAG_LONG_CARGO_TYPE_LISTS	New format for callbacks callbacks cargo_subtype_display, cargo_input, cargo_output to support more input/output cargos. See the callbacks for details.
IND_FLAG_DO_NOT_CLAMP_PASSENGER_PRODUCTION	NML 0.7 1.11 By default OpenTTD's smooth economy clamps the production of passenger (like for oil rigs). This flag disables the clamping.

Common variables

The following variables are available to both industries and industry tiles. All of them require an x, y offset. For industries, this offset is unsigned and relative to the northernmost tile. For industry tiles, it is signed and relative to the current tile.

name	value range	comment
nearby_tile_slope	SLOPE_XXX	See tile slopes for an overview of possible values
nearby_tile_is_water	1 if the tile is water, 0 otherwise
nearby_tile_terrain_type	TILETYPE_XX	TILETYPE_NORMAL, TILETYPE_DESERT, TILETYPE_RAIN_FOREST, TILETYPE_SNOW
nearby_tile_water_class	WATER_CLASS_XXX	XXX = [NONE | SEA | CANAL | RIVER] Note that tiles for which nearby_tile_is_water is 0 may still have a water class, e.g. industry tiles with water beneath them.
nearby_tile_height	0..120	The height of the lowest corner of the given tile.
nearby_tile_class	Tile class
nearby_tile_animation_frame	0..255	Animation frame of the given tile
nearby_tile_industrytile_id	0x00aa, 0xFFbb, 0xFFFE or 0xFFFF	0x00aa: The tile is an industry tile defined in this GRF with tile id aa. 0xFFbb: The tile is an original industry tile with id bb. 0xFFFE: The tile is an industry tile defined in another GRF. 0xFFFF: The tile is not an industry tile or it belongs to another industry.

Industry variables

name	value range	comment
production_level	0, or 4 .. 128	Current production level of the industry. Usually in range 4 .. 128, default starting level is 16. A level of 0 indicates imminent closure.
waiting_cargo_1	0..65535	If any of the production callbacks is enabled, this variable will contain the amount of the first cargo type awaiting to be processed. NML 0.5 Removed. Use incoming_cargo_waiting instead.
waiting_cargo_2	0..65535	If any of the production callbacks is enabled, this variable will contain the amount of the second cargo type awaiting to be processed. NML 0.5 Removed. Use incoming_cargo_waiting instead.
waiting_cargo_3	0..65535	If any of the production callbacks is enabled, this variable will contain the amount of the third cargo type awaiting to be processed. NML 0.5 Removed. Use incoming_cargo_waiting instead.
produced_cargo_waiting_1	0..65535	The amount of produced 'output cargo type 1' that this waiting to be transported. NML 0.5 Removed. Use produced_cargo_waiting instead.
produced_cargo_waiting_2	0..65535	The amount of produced 'output cargo type 2' that this waiting to be transported. NML 0.5 Removed. Use produced_cargo_waiting instead.
produced_this_month_1	0..65535	The amount of 'output cargo type 1' that was produced this month. NML 0.5 Removed. Use this_month_production instead.
produced_this_month_2	0..65535	The amount of 'output cargo type 2' that was produced this month. NML 0.5 Removed. Use this_month_production instead.
produced_last_month_1	0..65535	The amount of 'output cargo type 1' that was produced last month. NML 0.5 Removed. Use last_month_production instead.
produced_last_month_2	0..65535	The amount of 'output cargo type 2' that was produced last month. NML 0.5 Removed. Use last_month_production instead.
transported_this_month_1	0..65535	The amount of 'output cargo type 1' that was transported this month. NML 0.5 Removed. Use this_month_transported instead.
transported_this_month_2	0..65535	The amount of 'output cargo type 2' that was transported this month. NML 0.5 Removed. Use this_month_transported instead.
transported_last_month_1	0..65535	The amount of 'output cargo type 1' that was produced last month. NML 0.5 Removed. Use last_month_transported instead.
transported_last_month_2	0..65535	The amount of 'output cargo type 2' that was produced last month. NML 0.5 Removed. Use last_month_transported instead.
transported_last_month_pct_1	0..100	Percentage of produced 'output cargo type 1' that was transported last month. NML 0.5 Removed. Use transported_last_month_pct instead.
transported_last_month_pct_2	0..100	Percentage of produced 'output cargo type 2' that was transported last month. NML 0.5 Removed. Use transported_last_month_pct instead.
production_rate_1	0..255	NML 0.3 Amount of 'output cargo type 1' that is produced every 256 ticks. Initial value from the prod_multiplier-property, but it will change accordingly when the production level changes. NML 0.5 Removed. Use production_rate instead.
production_rate_2	0..255	NML 0.3 Amount of 'output cargo type 2' that is produced every 256 ticks. Initial value from the prod_multiplier-property, but it will change accordingly when the production level changes. NML 0.5 Removed. Use production_rate instead.
water_distance	Distance to the tile	If the industry is built on water, this variable gives the distance of the closest dry land tile, otherwise it gives the distance of the closest water tile.
layout_num	1..255	Number of the layout being used by the industry.
founder	0..16	Company number of the industry founder. It will be FOUNDER_GAME (=16) if the industry was generated randomly. TTDPatch only supports up to 8 companies (0..7).
founder_type	PLAYERTYPE_XX	PLAYERTYPE_HUMAN, PLAYERTYPE_AI, PLAYERTYPE_HUMAN_IN_AI (human managing AI company) or PLAYERTYPE_AI_IN_HUMAN (AI managing human company). OpenTTD only uses PLAYERTYPE_HUMAN and PLAYERTYPE_AI. If you cheat yourself to be part of an AI company OpenTTD will still report PLAYERTYPE_AI for the company with yourself and the AI and it'll report PLAYERTYPE_HUMAN for the now uncontrolled company.
founder_colour1	COLOUR_XXX	Index of founding company's first colour. 0 if not founded by a company. Refer to the table here for possible values.
founder_colour2	COLOUR_XXX	Index of founding company's second colour. It's the same as company_colour1, if no second company colour is chosen. 0 if not founded by a company. Refer to the table here for possible values.
colour	COLOUR_XXX	Random colour for this industry. Refer to the table here for possible values.
build_date	0..1826212865	Date of the industry foundation in days since year 0.
build_type	BUILDTYPE_XX	BUILDTYPE_UNKNOWN (if created in an old version or with newindustries disabled), BUILDTYPE_GAMEPLAY (if founded or created by the in-game random industry generator), BUILDTYPE_GENERATION (if created during random map generation) or BUILDTYPE_EDITOR (if created with the scenario editor).
counter	0..65535	Decremented every tick, used to time primary industry production in TTD.
last_accept_date	date(year, month, day)	Date when cargo was accepted for the last time. Not valid before 1920 and after 2090.
random_bits	0 ... 65535	Random data that can be used to randomize certain descisions. (see Random switch) (NML r1666)
gs_disallows_prod_decrease	[0 | 1]	NML 0.71.11 GameScript can optionally set a property that to indicate that production should not decrease at this industry. This will be automatically applied for organic and extractive industries, *if* the NewGRF industry production callback is *not* used *and* smooth economy is enabled. In other cases, NewGRF industries can provide behaviour as requested by the GameScript by reading this variable during production callbacks.
gs_disallows_prod_increase	[0 | 1]	NML 0.71.11 GameScript can optionally set a property that to indicate that production should not increase at this industry. This will be automatically applied for organic and extractive industries, *if* the NewGRF industry production callback is *not* used *and* smooth economy is enabled. In other cases, NewGRF industries can provide behaviour as requested by the GameScript by reading this variable during production callbacks.
gs_disallows_closure	[0 | 1]	NML 0.71.11 GameScript can optionally set a property that to indicate that this industry should not close. NewGRF industries can use this variable to read the property set by GameScript and provide the appropriate closure behaviour. Any closure already scheduled will still take place.

Variables that require some parameters.

name	arguments	comment
industry_count	industry_type, grfid = -1	The value of this variable is the number of industries of a given type that are currently on the map. industry_type is either the ID of an industry. GRFid is the grf in which the industry was defined. The default value is -1, which means current newgrf. A grfid of 0 lets you check the number of default industries of a given type. Use the builtin function str2number() to convert a grfid to its numeric representation. Warning: using this variable trashes the contents of temporary storage register 0x100
industry_distance	industry_type, grfid = -1	The value of this variable is the manhattan distance the closest instance of the given industry or 0xFFFF if not applicable. See industry_count for a description of the parameters. Warning: using this variable trashes the contents of temporary storage register 0x100.
industry_layout_count / industry_layout_distance	industry_type, layout, grfid = -1.	See industry_count / industry_distance for description of industry_type, grfid and return value. The results are filtered to industries that have the given layout number. Warning: using this variable trashes the contents of temporary storage registers 0x100 and 0x101.
industry_town_count	industry_type, grfid = -1.	See industry_count / industry_distance for description of industry_type, grfid and return value. The results are filtered to industries that have the same town than the current industry. Warning: using this variable trashes the contents of temporary storage registers 0x100 and 0x101.
town_manhattan_dist	x, y	Parameters indicate a signed offset relative to the northern tile. Returns the Manhattan distance (dx + dy) from the selected tile to the closest town
town_euclidean_dist	x, y	Parameters indicate a signed offset relative to the northern tile. Returns the squared Eucleidean distance (dx^2 + dy^2) from the selected tile to the closest town.
town_zone	x, y	Parameters indicate a signed offset relative to the northern tile. Returns the town zone that the selected tile is in.
nearby_tile_random_bits	x, y	Parameters indicate an unsigned offset relative to the northern tile. Returns the random bits of the selected industry tile, or 0 if it is not an industry tile that's part of this industry.
incoming_cargo_waiting	cargo label from the cargotable	NML 0.5 If any of the production callbacks is enabled, this variable will contain the amount of the cargo type waiting to be processed. Returns 0..65535. Example: incoming_cargo_waiting("FOOD").
produced_cargo_waiting	cargo label from the cargotable	NML 0.5 For the given cargo label, the amount of produced cargo that this waiting to be transported. Returns 0..65535. Example: produced_cargo_waiting("GOOD").
this_month_production	cargo label from the cargotable	NML 0.5 For the given cargo label, amount of cargo that was produced this month. Returns 0..65535. Example: this_month_production("COAL").
last_month_production	cargo label from the cargotable	NML 0.5 For the given cargo label, amount of cargo that was produced last month. Returns 0..65535. Example: last_month_production("WOOD").
this_month_transported	cargo label from the cargotable	NML 0.5 For the given cargo label, amount of produced cargo that was transported this month. Returns 0..65535. Example: this_month_transported("IORE").
last_month_transported	cargo label from the cargotable	NML 0.5 For the given cargo label, amount of produced cargo that was transported last month. Returns 0..65535. Example: last_month_transported("PAPR").
transported_last_month_pct	cargo label from the cargotable	NML 0.5 For the given cargo label, percentage of produced cargo that was transported last month. Returns 0..100. Example: transported_last_month_pct("BATT").
production_rate	cargo label from the cargotable	NML 0.5 For the given cargo label, amount of output cargo that is produced every 256 ticks. Initial value from the cargo_types property, but it will change accordingly when the production level changes. Returns 0..255. Example: production_rate("SUGR").

Industry callbacks

callback	return value	comment
default	varies	Any unhandled callbacks. Generally this doesn't need to be used, except for old-style callbacks.
produce_cargo_arrival	Produce-block	Called to produce cargo when it arrives.
produce_256_ticks	Produce-block	Called to produce cargo every 256 ticks.
availability	CB_RESULT_IND_ALLOW or CB_RESULT_IND_DISALLOW	NML 0.2 Only available in NML 0.2 or earlier. Called when the game needs to know if the industry type is available. It is limited to the type as a whole, so you can't access industry-specific variables. extra_callback_info2 contains the creation type.
construction_probability	CB_RESULT_IND_NO_CONSTRUCTION, CB_RESULT_IND_PROBABILITY_FROM_PROPERTY or a relative probability 0..255	NML 0.3. Called when the game needs to know if the industry type is available. It is limited to the type as a whole, so you can't access industry-specific variables. getbits(extra_callback_info2, 0, 8): The creation type. If you return CB_RESULT_IND_NO_CONSTRUCTION or 0 the industry won't be build. If you return CB_RESULT_IND_PROBABILITY_FROM_PROPERTY it'll be build according to the relative probability as defined in the prob_random or prob_in_game properties, otherwise it'll use the value as returned as relative probability.
location_check	See the table below.	Called to check if a location is suitable. getbits(extra_callback_info2, 0, 8): The creation type. Since the industry isn't built yet, industry variables aren't available. If this callback is not implemented or fails, constructing the industry will be allowed. Construction might also be prevented via the tile_check industry tile callback, though.
monthly_prod_change	See below	Called each month to (possibly) change the industry production. extra_callback_info2: 32 random bits.
random_prod_change	See below	Works exactly the same as monthly_prod_change, except that it's only called when TTD selects this industry for a random production change.
build_prod_change	Value in range 4-128	1.3 Called when an industry is constructed. Return value is production level (default 16). Can also be used to initialise permanent storage when an industry is constructed.
cargo_subtype_display	String, CB_RESULT_NO_TEXT or CB_RESULT_IND_NO_TEXT_NO_AMOUNT	This callback allows displaying some text after a cargo name. Returning CB_RESULT_NO_TEXT displays only waiting amount of cargo, CB_RESULT_IND_NO_TEXT_NO_AMOUNT displays only the cargotype. Note: To remove cargo waiting text, return 0x3800 + string(STR_EMPTY) where STR_EMPTY is an empty string in your lang file. If IND_FLAG_LONG_CARGO_TYPE_LISTS is not set: getbits(extra_callback_info2, 0, 8): 0 .. 2 to get texts for the first .. third accepted cargo type, and 3 .. 4 for the first ... second produced cargo type. getbits(extra_callback_info2, 8, 8): 0 when getting a string for the buy menu (no industry variables available!), 1 when for the industry window and 2 for the industry directory window. If IND_FLAG_LONG_CARGO_TYPE_LISTS is set: getbits(extra_callback_info2, 0, 8): 0 for output cargos, 1 for input cargos. getbits(extra_callback_info2, 8, 8): 0 when getting a string for the buy menu (no industry variables available!), 1 when for the industry window and 2 for the industry directory window. getbits(extra_callback_info2, 16, 8): Cargo type.
extra_text_industry	String	Show extra text in the industry window.
extra_text_fund	String	Show extra text in the fund window. Since the industry isn't built, no industry variables are available.
control_special	0 or 1	Called to control various effects from the spec_flags property. Currently only works for the first two (plant fields / cut trees). Return 1 to execute the action or 0 to not do so. extra_callback_info1: 32 random bits. getbits(extra_callback_info2, 0, 8): Queried effect. The default (if the flag is enabled, of course) is to plant fields with 1/8th chance every 256 ticks, and to cut trees every 512 ticks.
stop_accept_cargo	0 or 1	With this callback, you can temporarily refuse accepting a certain cargo, for example because the stockpile is full. Return 1 to accept or 0 to refuse. Make sure to synchronize this callback with the cargo_amount_accept callback for industry tiles. getbits(extra_callback_info2, 0, 8) The cargo type to accept or not.
colour	COLOUR_XXX	Called after constructing the industry. The colour variable is set to a random value at this point, you can use this callback to change this.
cargo_input	Cargo type, or 0xFF	Decide the input cargo types, called when the industry is built. Called repeatedly until 0xFF is returned, although currently not more than three times. Do not rely on this limitation, though. getbits(extra_callback_info1, 0, 8): Starts at 0 and is incremented for every iteration. Return a cargo type (from the table) or 0xFF to stop.
cargo_output	Cargo type, or 0xFF	Same as cargo_input above, except that it is applied to the output cargo types and currently not called more than twice.

Location check results

The following values can be used as return values for the location_check callback for industries and the tile_check callback for industry tiles and objects.

return value	meaning
string(..)	Item can't be built, show the string as error message.
CB_RESULT_LOCATION_ALLOW	Item can be built.
CB_RESULT_LOCATION_DISALLOW	Item can't be built, display the default error message. This is "site unsuitable" for industries and industry tiles, and "land sloped in wrong direction" for objects.
CB_RESULT_LOCATION_DISALLOW_ONLY_RAINFOREST	Item can't be built, display the "...can only be built in rainforest areas" error message.
CB_RESULT_LOCATION_DISALLOW_ONLY_DESERT	Item can't be built, display the "...can only be built in desert areas" error message.
CB_RESULT_LOCATION_DISALLOW_ONLY_ABOVE_SNOWLINE	Item can't be built, display the "...can only be built above the snow-line" error message.
CB_RESULT_LOCATION_DISALLOW_ONLY_BELOW_SNOWLINE	Item can't be built, display the "...can only be built below the snow-line" error message.
CB_RESULT_LOCATION_DISALLOW_NOT_ON_OPEN_SEA	Item can't be built, display the "...can't build on open sea" error message.
CB_RESULT_LOCATION_DISALLOW_NOT_ON_CANAL	Item can't be built, display the "...can't build on canal" error message
CB_RESULT_LOCATION_DISALLOW_NOT_ON_RIVER	Item can't be built, display the "...can't build on river" error message.

Production change callback results

value	meaning
CB_RESULT_IND_PROD_NO_CHANGE	Do not change industry production
CB_RESULT_IND_PROD_HALF	Half industry production. If production goes below a quarter of default, the industry closes.
CB_RESULT_IND_PROD_DOUBLE	Double production if it's not 8x default yet.
CB_RESULT_IND_PROD_CLOSE	Announce closure and remove the industry next month.
CB_RESULT_IND_PROD_RANDOM	Do a random production change, as if the industry is a primary one.
CB_RESULT_IND_PROD_DIVIDE_BY_4	Divide production by 4
CB_RESULT_IND_PROD_DIVIDE_BY_8	Divide production by 8
CB_RESULT_IND_PROD_DIVIDE_BY_16	Divide production by 16
CB_RESULT_IND_PROD_DIVIDE_BY_32	Divide production by 32
CB_RESULT_IND_PROD_MULTIPLY_BY_4	Multiply production by 4
CB_RESULT_IND_PROD_MULTIPLY_BY_8	Multiply production by 8
CB_RESULT_IND_PROD_MULTIPLY_BY_16	Multiply production by 16
CB_RESULT_IND_PROD_MULTIPLY_BY_32	Multiply production by 32
CB_RESULT_IND_PROD_DECREMENT_BY_1	Decrement production by 1
CB_RESULT_IND_PROD_INCREMENT_BY_1	Increment production by 1
CB_RESULT_IND_PROD_SET_BY_0x100	Set the production level to the value in bits 16 .. 23 of register 0x100.

Setting bit 7 of the result disables the associated news message.
Setting bit 8 replaces the news message with a custom message, read from register 0x100 bits 0 .. 15.

You can set specific bits in the return value by using a bitmask:

switch(FEAT_INDUSTRIES, SELF, upscale_production, [
    STORE_TEMP(STR_NEWS_INDUSTRY_PRODUCTION_INCREASE_CUSTOM, 0x100)
]) {
    return CB_RESULT_IND_PROD_DOUBLE | bitmask(8);
}

Industry creation types

value	meaning
IND_CREATION_GENERATION	Industry is created during map generation, or when building 'many random industries' in the scenario editor.
IND_CREATION_RANDOM	Industry is randomly generated during gameplay
IND_CREATION_FUND	Industry is funded by the player (in game or scenario editor)
IND_CREATION_PROSPECT	Industry is prospected by the player