diff --git a/newgrf_callbacks.h b/newgrf_callbacks.h
new file mode 100644
--- /dev/null
+++ b/newgrf_callbacks.h
@@ -0,0 +1,40 @@
+/* $Id$ */
+
+#ifndef NEWGRF_CALLBACKS_H
+#define NEWGRF_CALLBACKS_H
+
+/** @file newgrf_callbacks.h
+ */
+
+// This enum lists the implemented callbacks
+// Use as argument for the GetCallBackResult function (see comments there)
+enum CallbackID {
+	// Powered wagons, if the result is lower as 0x40 then the wagon is powered
+	// TODO: interpret the rest of the result, aka "visual effects"
+	CBID_WAGON_POWER = 0x10,
+
+	// Vehicle length, returns the amount of 1/8's the vehicle is shorter
+	// only for train vehicles
+	CBID_VEH_LENGTH = 0x11,
+
+	// Refit capacity, the passed vehicle needs to have its ->cargo_type set to
+	// the cargo we are refitting to, returns the new cargo capacity
+	CBID_REFIT_CAP = 0x15,
+
+	CBID_ARTIC_ENGINE = 0x16,
+};
+
+// bit positions for rvi->callbackmask, indicates which callbacks are used by an engine
+// (some callbacks are always used, and dont appear here)
+enum CallbackMask {
+	CBM_WAGON_POWER = 0,
+	CBM_VEH_LENGTH = 1,
+	CBM_REFIT_CAP = 3,
+	CBM_ARTIC_ENGINE = 4,
+};
+
+enum {
+	CALLBACK_FAILED = 0xFFFF
+};
+
+#endif /* NEWGRF_CALLBACKS_H */