Callback: Decide input and output cargo types
Decide input and output cargo types (14B,14C)
These callbacks are called when the industry is built, and allow customizing the input and output cargo types dynamically. However, you are only allowed to reduce the number of accepted/produced cargos. Industry properties 25 and 26 should always be a superset of the returned cargotypes.
Both callbacks are called repeatedly, with the lowest byte of variable 10 starting from zero and increasing after every call; you should return a cargo type each time, or FFh to terminate the list. (A failed callback terminates the list, too.) The same limitations apply as for callback 14A: industry tiles aren't yet placed, and some industry variables contain junk. You can use random action2s, however. The interpretation of the returned value depends on two factors: the current GRF version number and the presence of a cargo translation table:
|GRF version||Has cargo translation table||Interpretation|
|6 or below||Climate-dependent cargo slot number|
|7 or above||No||Cargo bit|
|7 or above||Yes||Index in the translation table|
The callback results replace the content of properties 25 and 26. If you use these callbacks, it is recommended to not use industry properties 12..13, 1C..1E and 27..28, which depend on the order of cargotypes, but instead use production callback version 2.
1.9 If industry property 1A flag 18 is clear, these callbacks are called at most for 3 input and 2 output cargos. If flag 18 is set, this compatibility restriction is removed and the callbacks are called more often.
In both cases return FFh as the last element to terminate the lists.