[BT :<X>,<Y>, <W>,<H> ]
[BT :<X1>,<Y1>,<W1>,,<X2>,<Y2>,<W2>,, ...
]
Block Transparent
A rectangular field is made transparent
Using this modifier you can mask out loads on open freight cars or exhaust on steam engines. It is possible to define the parameters <X>, <Y>, <W>, <H> more than once, thereby creating multiple transparent rectangular areas. This is a simpler method than using multiple [BT: ] commands.