diff --git a/src/micropolisj/engine/TileSpec.java b/src/micropolisj/engine/TileSpec.java
index ec44328..3d40c59 100644
--- a/src/micropolisj/engine/TileSpec.java
+++ b/src/micropolisj/engine/TileSpec.java
@@ -284,4 +284,65 @@ public class TileSpec
 	{
 		return "{tile#"+tileNumber+"}";
 	}
+
+	void resolveReferences(Map<String,TileSpec> tileMap)
+	{
+		String tmp = this.getAttribute("becomes");
+		if (tmp != null) {
+			this.animNext = tileMap.get(tmp);
+		}
+		tmp = this.getAttribute("onpower");
+		if (tmp != null) {
+			this.onPower = tileMap.get(tmp);
+		}
+		tmp = this.getAttribute("onshutdown");
+		if (tmp != null) {
+			this.onShutdown = tileMap.get(tmp);
+		}
+		tmp = this.getAttribute("building-part");
+		if (tmp != null) {
+			this.handleBuildingPart(tmp, tileMap);
+		}
+	}
+
+	private void handleBuildingPart(String text, Map<String,TileSpec> tileMap)
+	{
+		String [] parts = text.split(",");
+		if (parts.length != 3) {
+			throw new Error("Invalid building-part specification");
+		}
+
+		this.owner = tileMap.get(parts[0]);
+		this.ownerOffsetX = Integer.parseInt(parts[1]);
+		this.ownerOffsetY = Integer.parseInt(parts[2]);
+
+		assert this.owner != null;
+		assert this.ownerOffsetX != 0 || this.ownerOffsetY != 0;
+	}
+
+	public static String [] generateTileNames(Properties recipe)
+	{
+		int ntiles = recipe.size();
+		String [] tileNames = new String[ntiles];
+		ntiles = 0;
+		for (int i = 0; recipe.containsKey(Integer.toString(i)); i++) {
+			tileNames[ntiles++] = Integer.toString(i);
+		}
+		int naturalNumberTiles = ntiles;
+
+		for (Object n_obj : recipe.keySet()) {
+			String n = (String)n_obj;
+			if (n.matches("^\\d+$")) {
+				int x = Integer.parseInt(n);
+				if (x >= 0 && x < naturalNumberTiles) {
+					assert tileNames[x].equals(n);
+					continue;
+				}
+			}
+			assert ntiles < tileNames.length;
+			tileNames[ntiles++] = n;
+		}
+		assert ntiles == tileNames.length;
+		return tileNames;
+	}
 }
diff --git a/src/micropolisj/engine/Tiles.java b/src/micropolisj/engine/Tiles.java
index b769bbb..5d607ea 100644
--- a/src/micropolisj/engine/Tiles.java
+++ b/src/micropolisj/engine/Tiles.java
@@ -54,22 +54,8 @@ public class Tiles
 		tiles = tilesList.toArray(new TileSpec[0]);
 
 		for (int i = 0; i < tiles.length; i++) {
-			String tmp = tiles[i].getAttribute("becomes");
-			if (tmp != null) {
-				tiles[i].animNext = get(Integer.parseInt(tmp));
-			}
-			tmp = tiles[i].getAttribute("onpower");
-			if (tmp != null) {
-				tiles[i].onPower = get(Integer.parseInt(tmp));
-			}
-			tmp = tiles[i].getAttribute("onshutdown");
-			if (tmp != null) {
-				tiles[i].onShutdown = get(Integer.parseInt(tmp));
-			}
-			tmp = tiles[i].getAttribute("building-part");
-			if (tmp != null) {
-				handleBuildingPart(tiles[i], tmp);
-			}
+			tiles[i].resolveReferences(tilesByName);
+
 			TileSpec.BuildingInfo bi = tiles[i].getBuildingInfo();
 			if (bi != null) {
 				for (int j = 0; j < bi.members.length; j++) {
@@ -90,20 +76,6 @@ public class Tiles
 		}
 	}
 
-	private static void handleBuildingPart(TileSpec partTile, String tmp)
-	{
-		String [] parts = tmp.split(",");
-		if (parts.length != 3) {
-			throw new Error("Invalid building-part specification");
-		}
-
-		partTile.owner = get(Integer.parseInt(parts[0]));
-		partTile.ownerOffsetX = Integer.parseInt(parts[1]);
-		partTile.ownerOffsetY = Integer.parseInt(parts[2]);
-
-		assert partTile.ownerOffsetX != 0 || partTile.ownerOffsetY != 0;
-	}
-
 	public static TileSpec get(int tileNumber)
 	{
 		if (tileNumber >= 0 && tileNumber < tiles.length) {