diff --git a/src/order_base.h b/src/order_base.h
index a96879580d..d39f572c05 100644
--- a/src/order_base.h
+++ b/src/order_base.h
@@ -246,7 +246,7 @@ public:
 
 	/**
 	 * Gets the destination of this order.
-	 * @pre IsType(OT_GOTO_WAYPOINT) || IsType(OT_GOTO_DEPOT) || IsType(OT_GOTO_STATION) || IsType(OT_RELEASE_SLOT) || IsType(OT_COUNTER) || IsType(OT_LABEL).
+	 * @pre IsType(OT_GOTO_WAYPOINT) || IsType(OT_GOTO_DEPOT) || IsType(OT_GOTO_STATION) || IsType(OT_SLOT) || IsType(OT_COUNTER) || IsType(OT_LABEL).
 	 * @return the destination of the order.
 	 */
 	inline DestinationID GetDestination() const { return this->dest; }
@@ -254,7 +254,7 @@ public:
 	/**
 	 * Sets the destination of this order.
 	 * @param destination the new destination of the order.
-	 * @pre IsType(OT_GOTO_WAYPOINT) || IsType(OT_GOTO_DEPOT) || IsType(OT_GOTO_STATION) || IsType(OT_RELEASE_SLOT) || IsType(OT_COUNTER) || IsType(OT_LABEL).
+	 * @pre IsType(OT_GOTO_WAYPOINT) || IsType(OT_GOTO_DEPOT) || IsType(OT_GOTO_STATION) || IsType(OT_SLOT) || IsType(OT_COUNTER) || IsType(OT_LABEL).
 	 */
 	inline void SetDestination(DestinationID destination) { this->dest = destination; }
 
@@ -467,7 +467,7 @@ public:
 	 * explicitly set (but travel_time is actually unused for conditionals). */
 
 	/* Does this order not have any associated travel or wait times */
-	inline bool HasNoTimetableTimes() const { return this->IsType(OT_COUNTER) || this->IsType(OT_RELEASE_SLOT) || this->IsType(OT_LABEL); }
+	inline bool HasNoTimetableTimes() const { return this->IsType(OT_COUNTER) || this->IsType(OT_SLOT) || this->IsType(OT_LABEL); }
 
 	/** Does this order have an explicit wait time set? */
 	inline bool IsWaitTimetabled() const
@@ -635,6 +635,11 @@ public:
 		}
 	}
 
+	inline OrderSlotSubType GetSlotSubType() const
+	{
+		return (OrderSlotSubType)GB(this->flags, 0, 8);
+	}
+
 	inline OrderLabelSubType GetLabelSubType() const
 	{
 		return (OrderLabelSubType)GB(this->flags, 0, 8);
diff --git a/src/order_cmd.cpp b/src/order_cmd.cpp
index 3ead40b8d9..1f9f31f44e 100644
--- a/src/order_cmd.cpp
+++ b/src/order_cmd.cpp
@@ -242,8 +242,9 @@ void Order::MakeLoadingAdvance(StationID destination)
 
 void Order::MakeReleaseSlot()
 {
-	this->type = OT_RELEASE_SLOT;
+	this->type = OT_SLOT;
 	this->dest = INVALID_TRACE_RESTRICT_SLOT_ID;
+	this->flags = OSST_RELEASE;
 }
 
 void Order::MakeChangeCounter()
@@ -705,7 +706,7 @@ CargoMaskedStationIDStack OrderList::GetNextStoppingStation(const Vehicle *v, Ca
 			});
 			if (invalid) return CargoMaskedStationIDStack(cargo_mask, INVALID_STATION);
 		}
-	} while (next->IsType(OT_GOTO_DEPOT) || next->IsType(OT_RELEASE_SLOT) || next->IsType(OT_COUNTER) || next->IsType(OT_DUMMY) || next->IsType(OT_LABEL)
+	} while (next->IsType(OT_GOTO_DEPOT) || next->IsType(OT_SLOT) || next->IsType(OT_COUNTER) || next->IsType(OT_DUMMY) || next->IsType(OT_LABEL)
 			|| (next->IsBaseStationOrder() && next->GetDestination() == v->last_station_visited));
 
 	return CargoMaskedStationIDStack(cargo_mask, next->GetDestination());
@@ -1268,12 +1269,19 @@ CommandCost CmdInsertOrderIntl(DoCommandFlag flags, Vehicle *v, VehicleOrderID s
 			break;
 		}
 
-		case OT_RELEASE_SLOT: {
+		case OT_SLOT: {
 			TraceRestrictSlotID data = new_order.GetDestination();
 			if (data != INVALID_TRACE_RESTRICT_SLOT_ID) {
 				const TraceRestrictSlot *slot = TraceRestrictSlot::GetIfValid(data);
 				if (slot == nullptr || slot->vehicle_type != v->type) return CMD_ERROR;
 			}
+			switch (new_order.GetSlotSubType()) {
+				case OSST_RELEASE:
+					break;
+
+				default:
+					return CMD_ERROR;
+			}
 			break;
 		}
 
@@ -1839,7 +1847,7 @@ CommandCost CmdModifyOrder(TileIndex tile, DoCommandFlag flags, uint32_t p1, uin
 				if (mof != MOF_COND_VARIABLE && mof != MOF_COND_COMPARATOR && mof != MOF_COND_VALUE && mof != MOF_COND_VALUE_2 && mof != MOF_COND_VALUE_3 && mof != MOF_COND_DESTINATION && mof != MOF_COND_STATION_ID) return CMD_ERROR;
 				break;
 
-			case OT_RELEASE_SLOT:
+			case OT_SLOT:
 				if (mof != MOF_SLOT) return CMD_ERROR;
 				break;
 
@@ -3239,10 +3247,14 @@ VehicleOrderID AdvanceOrderIndexDeferred(const Vehicle *v, VehicleOrderID index)
 					return index;
 				}
 
-			case OT_RELEASE_SLOT:
+			case OT_SLOT:
 				if (TraceRestrictSlot::IsValidID(order->GetDestination())) {
-					include(_pco_deferred_slot_releases, order->GetDestination());
-					container_unordered_remove(_pco_deferred_slot_acquires, order->GetDestination());
+					switch (order->GetSlotSubType()) {
+						case OSST_RELEASE:
+							include(_pco_deferred_slot_releases, order->GetDestination());
+							container_unordered_remove(_pco_deferred_slot_acquires, order->GetDestination());
+							break;
+					}
 				}
 				break;
 
@@ -3414,11 +3426,17 @@ bool UpdateOrderDest(Vehicle *v, const Order *order, int conditional_depth, bool
 			break;
 		}
 
-		case OT_RELEASE_SLOT:
+		case OT_SLOT:
 			assert(!pbs_look_ahead);
 			if (order->GetDestination() != INVALID_TRACE_RESTRICT_SLOT_ID) {
 				TraceRestrictSlot *slot = TraceRestrictSlot::GetIfValid(order->GetDestination());
-				if (slot != nullptr) slot->Vacate(v->index);
+				if (slot != nullptr) {
+					switch (order->GetSlotSubType()) {
+						case OSST_RELEASE:
+							slot->Vacate(v->index);
+							break;
+					}
+				}
 			}
 			UpdateVehicleTimetable(v, true);
 			v->IncrementRealOrderIndex();
@@ -3718,7 +3736,7 @@ const char *GetOrderTypeName(OrderType order_type)
 		"OT_IMPLICIT",
 		"OT_WAITING",
 		"OT_LOADING_ADVANCE",
-		"OT_RELEASE_SLOT",
+		"OT_SLOT",
 		"OT_COUNTER",
 		"OT_LABEL",
 	};
diff --git a/src/order_gui.cpp b/src/order_gui.cpp
index 64bfcd5946..589c0c476e 100644
--- a/src/order_gui.cpp
+++ b/src/order_gui.cpp
@@ -1169,8 +1169,16 @@ void DrawOrderString(const Vehicle *v, const Order *order, int order_index, int
 			break;
 		}
 
-		case OT_RELEASE_SLOT:
-			SetDParam(0, STR_ORDER_RELEASE_SLOT);
+		case OT_SLOT:
+			switch (order->GetSlotSubType()) {
+				case OSST_RELEASE:
+					SetDParam(0, STR_ORDER_RELEASE_SLOT);
+					break;
+
+				default:
+					NOT_REACHED();
+					break;
+			}
 			if (order->GetDestination() == INVALID_TRACE_RESTRICT_SLOT_ID) {
 				SetDParam(1, STR_TRACE_RESTRICT_VARIABLE_UNDEFINED_RED);
 			} else {
@@ -2296,7 +2304,7 @@ public:
 					break;
 				}
 
-				case OT_RELEASE_SLOT: {
+				case OT_SLOT: {
 					if (row_sel != nullptr) {
 						row_sel->SetDisplayedPlane(DP_ROW_SLOT);
 					} else {
@@ -2612,7 +2620,7 @@ public:
 				VehicleOrderID sel = this->OrderGetSel();
 				const Order *order = this->vehicle->GetOrder(sel);
 
-				if (order != nullptr && order->IsType(OT_RELEASE_SLOT)) {
+				if (order != nullptr && order->IsType(OT_SLOT)) {
 					TraceRestrictSlotID value = order->GetDestination();
 					SetDParam(0, value);
 				}
diff --git a/src/order_type.h b/src/order_type.h
index c75e273f0c..1f5967f2e9 100644
--- a/src/order_type.h
+++ b/src/order_type.h
@@ -46,12 +46,16 @@ enum OrderType : byte {
 	OT_IMPLICIT      = 8,
 	OT_WAITING       = 9,
 	OT_LOADING_ADVANCE = 10,
-	OT_RELEASE_SLOT  = 11,
+	OT_SLOT          = 11,
 	OT_COUNTER       = 12,
 	OT_LABEL         = 13,
 	OT_END
 };
 
+enum OrderSlotSubType : byte {
+	OSST_RELEASE               = 0,
+};
+
 enum OrderLabelSubType : byte {
 	OLST_TEXT                  = 0,
 	OLST_DEPARTURES_VIA        = 1,
diff --git a/src/timetable_cmd.cpp b/src/timetable_cmd.cpp
index d95ba9c980..8df66a176d 100644
--- a/src/timetable_cmd.cpp
+++ b/src/timetable_cmd.cpp
@@ -713,8 +713,8 @@ std::vector<TimetableProgress> PopulateSeparationState(const Vehicle *v_start)
 			// Do not try to separate vehicles on depot service or halt orders
 			separation_valid = false;
 		}
-		if (order->IsType(OT_RELEASE_SLOT) || order->IsType(OT_COUNTER) || order->IsType(OT_DUMMY) || order->IsType(OT_LABEL)) {
-			// Do not try to separate vehicles on release slot, change counter, or invalid orders
+		if (order->IsType(OT_SLOT) || order->IsType(OT_COUNTER) || order->IsType(OT_DUMMY) || order->IsType(OT_LABEL)) {
+			// Do not try to separate vehicles on slot, change counter, or invalid orders
 			separation_valid = false;
 		}
 		int order_ticks;
diff --git a/src/tracerestrict.cpp b/src/tracerestrict.cpp
index c5f1e6c7e1..3bca02dbac 100644
--- a/src/tracerestrict.cpp
+++ b/src/tracerestrict.cpp
@@ -2778,7 +2778,7 @@ void TraceRestrictRemoveSlotID(TraceRestrictSlotID index)
 			o->GetXDataRef() = INVALID_TRACE_RESTRICT_SLOT_ID;
 			changed_order = true;
 		}
-		if (o->IsType(OT_RELEASE_SLOT) && o->GetDestination() == index) {
+		if (o->IsType(OT_SLOT) && o->GetDestination() == index) {
 			o->SetDestination(INVALID_TRACE_RESTRICT_SLOT_ID);
 			changed_order = true;
 		}
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index a2fc42ed69..bdc16b379a 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -4435,7 +4435,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 		 * the destination but instead to the next one if service isn't needed. */
 		CheckIfTrainNeedsService(v);
 		if (v->current_order.IsType(OT_DUMMY) || v->current_order.IsType(OT_CONDITIONAL) || v->current_order.IsType(OT_GOTO_DEPOT) ||
-				v->current_order.IsType(OT_RELEASE_SLOT) || v->current_order.IsType(OT_COUNTER) || v->current_order.IsType(OT_LABEL)) {
+				v->current_order.IsType(OT_SLOT) || v->current_order.IsType(OT_COUNTER) || v->current_order.IsType(OT_LABEL)) {
 			ProcessOrders(v);
 		}
 	}
@@ -6548,7 +6548,7 @@ static bool TrainLocoHandler(Train *v, bool mode)
 	/* exit if train is stopped */
 	if ((v->vehstatus & VS_STOPPED) && v->cur_speed == 0) return true;
 
-	bool valid_order = !v->current_order.IsType(OT_NOTHING) && v->current_order.GetType() != OT_CONDITIONAL && !v->current_order.IsType(OT_RELEASE_SLOT) && !v->current_order.IsType(OT_COUNTER) && !v->current_order.IsType(OT_LABEL);
+	bool valid_order = !v->current_order.IsType(OT_NOTHING) && v->current_order.GetType() != OT_CONDITIONAL && !v->current_order.IsType(OT_SLOT) && !v->current_order.IsType(OT_COUNTER) && !v->current_order.IsType(OT_LABEL);
 	if (ProcessOrders(v) && CheckReverseTrain(v)) {
 		v->wait_counter = 0;
 		v->cur_speed = 0;