dst = engine->u.rail.other_multiheaded_part;

					}

					break;

				}

		}

	}

	if (IsMultiheaded(src) && !IsTrainEngine(src)) return_cmd_error(STR_REAR_ENGINE_FOLLOW_FRONT_ERROR);

	{

		int r, num = 0;

		r = CheckTrainStoppedInDepot(src_head);

		/* check if all vehicles in the source train are stopped inside a depot */

		if (r < 0) return CMD_ERROR;

		num += r;

		/* check if all the vehicles in the dest train are stopped */

		if (dst_head != NULL) {

			r = CheckTrainStoppedInDepot(dst_head);

			if (r < 0) return CMD_ERROR;

			num += r;

			assert(dst_head->tile == src_head->tile);

		}

		/* Check that the length of the dest train is no longer than XXX vehicles */

		if (num > (_patches.mammoth_trains ? 100 : 9) && IsFrontEngine(dst_head))

			return_cmd_error(STR_8819_TRAIN_TOO_LONG);

	}

	// when moving all wagons, we can't have the same src_head and dst_head

	if (HASBIT(p2, 0) && src_head == dst_head) return 0;

	// moving a loco to a new line?, then we need to assign a unitnumber.

	if (dst == NULL && !IsFrontEngine(src) && IsTrainEngine(src)) {

		UnitID unit_num = GetFreeUnitNumber(VEH_Train);

		if (unit_num > _patches.max_trains)

			return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);

		if (flags & DC_EXEC)

			src->unitnumber = unit_num;

	}