Callback: Opt out of accepting cargo
Opt out of accepting cargo (3D)
With this callback, the industry can refuse accepting a cargo even if it's one of the input cargo types. If there's another industry nearby that accepts this cargo, that one will get it.
The lowest byte of var. 18 contains the ID of the cargo delivered. If your GRF has a cargo translation table installed, you will get the index from that table; otherwise, you will get the cargo bit associated with the cargo type. You must return zero if you don't want to accept the cargo, or 1 to accept it. Other return values are reserved for future use.
This callback should be used in conjunction with callback 2B, since the acceptance of the tiles and the acceptance of the industry itself should always agree. If you disable accepting a cargo via callback 3D, but forget to remove the acceptance from the tiles, the station will keep accepting the cargo and the player will keep getting the money, but the industry won't receive the cargo. On the other hand, if you remove acceptance from the tiles, but forget using callback 3D, your industry may still get the cargo. (For example, there may be another industry nearby whose tiles accept the cargo. This makes the station accept the cargo, and send it to the nearest industry, which happens to be yours, even though its tiles don't accept the cargo.)