Build Mask (.locked)

The build mask of a town is stored in ./iso/towns/<id>.locked (LockFormat=locked in iso.ini).

It is a flat array of one byte per tile covering the town area only (128 x 226 = 28928 bytes, no header).

ValueMeaning
0x00buildable
0x01locked

The entry for column x and row y (0..225) is the byte at y * 128 + x. The covered area matches rows 0..225 of the town map.