diff --git a/src/newgrf_airport.cpp b/src/newgrf_airport.cpp
index d757f0e9c3..f41ab15714 100644
--- a/src/newgrf_airport.cpp
+++ b/src/newgrf_airport.cpp
@@ -175,7 +175,7 @@ void AirportOverrideManager::SetEntitySpec(AirportSpec *as)
 {
 	byte airport_id = this->AddEntityID(as->grf_prop.local_id, as->grf_prop.grffile->grfid, as->grf_prop.subst_id);
 
-	if (airport_id == this->invalid_ID) {
+	if (airport_id == this->invalid_id) {
 		grfmsg(1, "Airport.SetEntitySpec: Too many airports allocated. Ignoring.");
 		return;
 	}
@@ -190,7 +190,7 @@ void AirportOverrideManager::SetEntitySpec(AirportSpec *as)
 
 		overridden_as->grf_prop.override = airport_id;
 		overridden_as->enabled = false;
-		this->entity_overrides[i] = this->invalid_ID;
+		this->entity_overrides[i] = this->invalid_id;
 		this->grfid_overrides[i] = 0;
 	}
 }
diff --git a/src/newgrf_airporttiles.cpp b/src/newgrf_airporttiles.cpp
index e6aa049112..91ae79f2d8 100644
--- a/src/newgrf_airporttiles.cpp
+++ b/src/newgrf_airporttiles.cpp
@@ -67,7 +67,7 @@ void AirportTileOverrideManager::SetEntitySpec(const AirportTileSpec *airpts)
 {
 	StationGfx airpt_id = this->AddEntityID(airpts->grf_prop.local_id, airpts->grf_prop.grffile->grfid, airpts->grf_prop.subst_id);
 
-	if (airpt_id == this->invalid_ID) {
+	if (airpt_id == this->invalid_id) {
 		grfmsg(1, "AirportTile.SetEntitySpec: Too many airport tiles allocated. Ignoring.");
 		return;
 	}
@@ -82,7 +82,7 @@ void AirportTileOverrideManager::SetEntitySpec(const AirportTileSpec *airpts)
 
 		overridden_airpts->grf_prop.override = airpt_id;
 		overridden_airpts->enabled = false;
-		this->entity_overrides[i] = this->invalid_ID;
+		this->entity_overrides[i] = this->invalid_id;
 		this->grfid_overrides[i] = 0;
 	}
 }
diff --git a/src/newgrf_commons.cpp b/src/newgrf_commons.cpp
index 907e7093c4..eb8d3f8c40 100644
--- a/src/newgrf_commons.cpp
+++ b/src/newgrf_commons.cpp
@@ -41,12 +41,12 @@
 OverrideManagerBase::OverrideManagerBase(uint16 offset, uint16 maximum, uint16 invalid)
 {
 	this->max_offset = offset;
-	this->max_new_entities = maximum;
-	this->invalid_ID = invalid;
+	this->max_entities = maximum;
+	this->invalid_id = invalid;
 
-	this->mapping_ID.resize(this->max_new_entities);
+	this->mappings.resize(this->max_entities);
 	this->entity_overrides.resize(this->max_offset);
-	std::fill(this->entity_overrides.begin(), this->entity_overrides.end(), this->invalid_ID);
+	std::fill(this->entity_overrides.begin(), this->entity_overrides.end(), this->invalid_id);
 	this->grfid_overrides.resize(this->max_offset);
 }
 
@@ -62,7 +62,7 @@ void OverrideManagerBase::Add(uint8 local_id, uint32 grfid, uint entity_type)
 {
 	assert(entity_type < this->max_offset);
 	/* An override can be set only once */
-	if (this->entity_overrides[entity_type] != this->invalid_ID) return;
+	if (this->entity_overrides[entity_type] != this->invalid_id) return;
 	this->entity_overrides[entity_type] = local_id;
 	this->grfid_overrides[entity_type] = grfid;
 }
@@ -70,13 +70,13 @@ void OverrideManagerBase::Add(uint8 local_id, uint32 grfid, uint entity_type)
 /** Resets the mapping, which is used while initializing game */
 void OverrideManagerBase::ResetMapping()
 {
-	std::fill(this->mapping_ID.begin(), this->mapping_ID.end(), EntityIDMapping{});
+	std::fill(this->mappings.begin(), this->mappings.end(), EntityIDMapping{});
 }
 
 /** Resets the override, which is used while initializing game */
 void OverrideManagerBase::ResetOverride()
 {
-	std::fill(this->entity_overrides.begin(), this->entity_overrides.end(), this->invalid_ID);
+	std::fill(this->entity_overrides.begin(), this->entity_overrides.end(), this->invalid_id);
 	std::fill(this->grfid_overrides.begin(), this->grfid_overrides.end(), uint32());
 }
 
@@ -88,14 +88,14 @@ void OverrideManagerBase::ResetOverride()
  */
 uint16 OverrideManagerBase::GetID(uint8 grf_local_id, uint32 grfid) const
 {
-	for (uint16 id = 0; id < this->max_new_entities; id++) {
-		const EntityIDMapping *map = &this->mapping_ID[id];
+	for (uint16 id = 0; id < this->max_entities; id++) {
+		const EntityIDMapping *map = &this->mappings[id];
 		if (map->entity_id == grf_local_id && map->grfid == grfid) {
 			return id;
 		}
 	}
 
-	return this->invalid_ID;
+	return this->invalid_id;
 }
 
 /**
@@ -113,11 +113,11 @@ uint16 OverrideManagerBase::AddEntityID(byte grf_local_id, uint32 grfid, byte su
 	 * separately from the loop below in case a GRF has been deleted, and there
 	 * are any gaps in the array.
 	 */
-	if (id != this->invalid_ID) return id;
+	if (id != this->invalid_id) return id;
 
 	/* This entity hasn't been defined before, so give it an ID now. */
-	for (id = this->max_offset; id < this->max_new_entities; id++) {
-		EntityIDMapping *map = &this->mapping_ID[id];
+	for (id = this->max_offset; id < this->max_entities; id++) {
+		EntityIDMapping *map = &this->mappings[id];
 
 		if (CheckValidNewID(id) && map->entity_id == 0 && map->grfid == 0) {
 			map->entity_id     = grf_local_id;
@@ -127,7 +127,7 @@ uint16 OverrideManagerBase::AddEntityID(byte grf_local_id, uint32 grfid, byte su
 		}
 	}
 
-	return this->invalid_ID;
+	return this->invalid_id;
 }
 
 /**
@@ -137,7 +137,7 @@ uint16 OverrideManagerBase::AddEntityID(byte grf_local_id, uint32 grfid, byte su
  */
 uint32 OverrideManagerBase::GetGRFID(uint16 entity_id) const
 {
-	return this->mapping_ID[entity_id].grfid;
+	return this->mappings[entity_id].grfid;
 }
 
 /**
@@ -147,7 +147,7 @@ uint32 OverrideManagerBase::GetGRFID(uint16 entity_id) const
  */
 uint16 OverrideManagerBase::GetSubstituteID(uint16 entity_id) const
 {
-	return this->mapping_ID[entity_id].substitute_id;
+	return this->mappings[entity_id].substitute_id;
 }
 
 /**
@@ -159,7 +159,7 @@ void HouseOverrideManager::SetEntitySpec(const HouseSpec *hs)
 {
 	HouseID house_id = this->AddEntityID(hs->grf_prop.local_id, hs->grf_prop.grffile->grfid, hs->grf_prop.subst_id);
 
-	if (house_id == this->invalid_ID) {
+	if (house_id == this->invalid_id) {
 		grfmsg(1, "House.SetEntitySpec: Too many houses allocated. Ignoring.");
 		return;
 	}
@@ -173,7 +173,7 @@ void HouseOverrideManager::SetEntitySpec(const HouseSpec *hs)
 		if (this->entity_overrides[i] != hs->grf_prop.local_id || this->grfid_overrides[i] != hs->grf_prop.grffile->grfid) continue;
 
 		overridden_hs->grf_prop.override = house_id;
-		this->entity_overrides[i] = this->invalid_ID;
+		this->entity_overrides[i] = this->invalid_id;
 		this->grfid_overrides[i] = 0;
 	}
 }
@@ -187,14 +187,14 @@ void HouseOverrideManager::SetEntitySpec(const HouseSpec *hs)
 uint16 IndustryOverrideManager::GetID(uint8 grf_local_id, uint32 grfid) const
 {
 	uint16 id = OverrideManagerBase::GetID(grf_local_id, grfid);
-	if (id != this->invalid_ID) return id;
+	if (id != this->invalid_id) return id;
 
 	/* No mapping found, try the overrides */
 	for (id = 0; id < this->max_offset; id++) {
 		if (this->entity_overrides[id] == grf_local_id && this->grfid_overrides[id] == grfid) return id;
 	}
 
-	return this->invalid_ID;
+	return this->invalid_id;
 }
 
 /**
@@ -207,9 +207,9 @@ uint16 IndustryOverrideManager::GetID(uint8 grf_local_id, uint32 grfid) const
 uint16 IndustryOverrideManager::AddEntityID(byte grf_local_id, uint32 grfid, byte substitute_id)
 {
 	/* This entity hasn't been defined before, so give it an ID now. */
-	for (uint16 id = 0; id < this->max_new_entities; id++) {
+	for (uint16 id = 0; id < this->max_entities; id++) {
 		/* Skip overridden industries */
-		if (id < this->max_offset && this->entity_overrides[id] != this->invalid_ID) continue;
+		if (id < this->max_offset && this->entity_overrides[id] != this->invalid_id) continue;
 
 		/* Get the real live industry */
 		const IndustrySpec *inds = GetIndustrySpec(id);
@@ -218,7 +218,7 @@ uint16 IndustryOverrideManager::AddEntityID(byte grf_local_id, uint32 grfid, byt
 		 * And it must not already be used by a grf (grffile == nullptr).
 		 * So reserve this slot here, as it is the chosen one */
 		if (!inds->enabled && inds->grf_prop.grffile == nullptr) {
-			EntityIDMapping *map = &this->mapping_ID[id];
+			EntityIDMapping *map = &this->mappings[id];
 
 			if (map->entity_id == 0 && map->grfid == 0) {
 				/* winning slot, mark it as been used */
@@ -230,7 +230,7 @@ uint16 IndustryOverrideManager::AddEntityID(byte grf_local_id, uint32 grfid, byt
 		}
 	}
 
-	return this->invalid_ID;
+	return this->invalid_id;
 }
 
 /**
@@ -244,16 +244,16 @@ void IndustryOverrideManager::SetEntitySpec(IndustrySpec *inds)
 	/* First step : We need to find if this industry is already specified in the savegame data. */
 	IndustryType ind_id = this->GetID(inds->grf_prop.local_id, inds->grf_prop.grffile->grfid);
 
-	if (ind_id == this->invalid_ID) {
+	if (ind_id == this->invalid_id) {
 		/* Not found.
 		 * Or it has already been overridden, so you've lost your place.
 		 * Or it is a simple substitute.
 		 * We need to find a free available slot */
 		ind_id = this->AddEntityID(inds->grf_prop.local_id, inds->grf_prop.grffile->grfid, inds->grf_prop.subst_id);
-		inds->grf_prop.override = this->invalid_ID;  // make sure it will not be detected as overridden
+		inds->grf_prop.override = this->invalid_id;  // make sure it will not be detected as overridden
 	}
 
-	if (ind_id == this->invalid_ID) {
+	if (ind_id == this->invalid_id) {
 		grfmsg(1, "Industry.SetEntitySpec: Too many industries allocated. Ignoring.");
 		return;
 	}
@@ -268,7 +268,7 @@ void IndustryTileOverrideManager::SetEntitySpec(const IndustryTileSpec *its)
 {
 	IndustryGfx indt_id = this->AddEntityID(its->grf_prop.local_id, its->grf_prop.grffile->grfid, its->grf_prop.subst_id);
 
-	if (indt_id == this->invalid_ID) {
+	if (indt_id == this->invalid_id) {
 		grfmsg(1, "IndustryTile.SetEntitySpec: Too many industry tiles allocated. Ignoring.");
 		return;
 	}
@@ -283,7 +283,7 @@ void IndustryTileOverrideManager::SetEntitySpec(const IndustryTileSpec *its)
 
 		overridden_its->grf_prop.override = indt_id;
 		overridden_its->enabled = false;
-		this->entity_overrides[i] = this->invalid_ID;
+		this->entity_overrides[i] = this->invalid_id;
 		this->grfid_overrides[i] = 0;
 	}
 }
@@ -299,7 +299,7 @@ void ObjectOverrideManager::SetEntitySpec(ObjectSpec *spec)
 	/* First step : We need to find if this object is already specified in the savegame data. */
 	ObjectType type = this->GetID(spec->grf_prop.local_id, spec->grf_prop.grffile->grfid);
 
-	if (type == this->invalid_ID) {
+	if (type == this->invalid_id) {
 		/* Not found.
 		 * Or it has already been overridden, so you've lost your place.
 		 * Or it is a simple substitute.
@@ -307,7 +307,7 @@ void ObjectOverrideManager::SetEntitySpec(ObjectSpec *spec)
 		type = this->AddEntityID(spec->grf_prop.local_id, spec->grf_prop.grffile->grfid, OBJECT_TRANSMITTER);
 	}
 
-	if (type == this->invalid_ID) {
+	if (type == this->invalid_id) {
 		grfmsg(1, "Object.SetEntitySpec: Too many objects allocated. Ignoring.");
 		return;
 	}
diff --git a/src/newgrf_commons.h b/src/newgrf_commons.h
index 3fdff6c78a..bf338c2da5 100644
--- a/src/newgrf_commons.h
+++ b/src/newgrf_commons.h
@@ -194,14 +194,14 @@ protected:
 	std::vector<uint16> entity_overrides;
 	std::vector<uint32> grfid_overrides;
 
-	uint16 max_offset;       ///< what is the length of the original entity's array of specs
-	uint16 max_new_entities; ///< what is the amount of entities, old and new summed
+	uint16 max_offset;   ///< what is the length of the original entity's array of specs
+	uint16 max_entities; ///< what is the amount of entities, old and new summed
 
-	uint16 invalid_ID;       ///< ID used to detected invalid entities;
+	uint16 invalid_id;   ///< ID used to detected invalid entities;
 	virtual bool CheckValidNewID(uint16 testid) { return true; }
 
 public:
-	std::vector<EntityIDMapping> mapping_ID; ///< mapping of ids from grf files.  Public out of convenience
+	std::vector<EntityIDMapping> mappings; ///< mapping of ids from grf files.  Public out of convenience
 
 	OverrideManagerBase(uint16 offset, uint16 maximum, uint16 invalid);
 	virtual ~OverrideManagerBase() {}
@@ -216,7 +216,7 @@ public:
 	uint16 GetSubstituteID(uint16 entity_id) const;
 	virtual uint16 GetID(uint8 grf_local_id, uint32 grfid) const;
 
-	inline uint16 GetMaxMapping() const { return this->max_new_entities; }
+	inline uint16 GetMaxMapping() const { return this->max_entities; }
 	inline uint16 GetMaxOffset() const { return this->max_offset; }
 };
 
diff --git a/src/saveload/newgrf_sl.cpp b/src/saveload/newgrf_sl.cpp
index 5dde97132c..d15057564a 100644
--- a/src/saveload/newgrf_sl.cpp
+++ b/src/saveload/newgrf_sl.cpp
@@ -32,10 +32,10 @@ void NewGRFMappingChunkHandler::Save() const
 	SlTableHeader(_newgrf_mapping_desc);
 
 	for (uint i = 0; i < this->mapping.GetMaxMapping(); i++) {
-		if (this->mapping.mapping_ID[i].grfid == 0 &&
-			this->mapping.mapping_ID[i].entity_id == 0) continue;
+		if (this->mapping.mappings[i].grfid == 0 &&
+			this->mapping.mappings[i].entity_id == 0) continue;
 		SlSetArrayIndex(i);
-		SlObject(&this->mapping.mapping_ID[i], _newgrf_mapping_desc);
+		SlObject(&this->mapping.mappings[i], _newgrf_mapping_desc);
 	}
 }
 
@@ -55,7 +55,7 @@ void NewGRFMappingChunkHandler::Load() const
 	int index;
 	while ((index = SlIterateArray()) != -1) {
 		if ((uint)index >= max_id) SlErrorCorrupt("Too many NewGRF entity mappings");
-		SlObject(&this->mapping.mapping_ID[index], slt);
+		SlObject(&this->mapping.mappings[index], slt);
 	}
 }