Configuring the Minecart-Type Detector Rail Edit
The rail is configured by placing a sign either 1 block above it or 2 blocks below it and indicating the desired type and output. Both signs may be used for up to 8 different detections. In the case of multiple minecarts being in the detection area, the highest value matched is output.
The syntax is simple: [name of cart]=[value] or [name of cart]:[value]
The name is a simple match with the end of the item name (case insensitive), e.g. "Furnace" will match "Minecart with Furnace". This should work for all vanilla carts, mod-added carts, and localization.
Additionally "Empty" will match an empty minecart, and "Command" will match the command block minecart.