The types set repeat: in the above example it repeats every 5 minecarts. The first two minecarts get a wooden block, the next three minecarts a stone block. Not specifying an amount is seen as infinite - which means that the specified block type counts for all carts. The following example shows a train set to use a diamond block for the first cart, a gold block for the next two carts, and empty (air) for all the remaining carts: