--- ../src-base/minecraft/net/minecraft/world/storage/WorldInfo.java
+++ ../src-work/minecraft/net/minecraft/world/storage/WorldInfo.java
@@ -66,6 +66,7 @@
     private int field_176155_J = 15;
     private final Map<DimensionType, NBTTagCompound> field_186348_N = Maps.newEnumMap(DimensionType.class);
     private GameRules field_82577_x = new GameRules();
+    private java.util.Map<String, net.minecraft.nbt.NBTBase> additionalProperties;
 
     protected WorldInfo()
     {
@@ -335,6 +336,7 @@
         nbttagcompound.func_74757_a("Snapshot", false);
         p_76064_1_.func_74782_a("Version", nbttagcompound);
         p_76064_1_.func_74768_a("DataVersion", 819);
+        net.minecraftforge.fml.common.FMLCommonHandler.instance().getDataFixer().writeVersionData(p_76064_1_);
         p_76064_1_.func_74772_a("RandomSeed", this.field_76100_a);
         p_76064_1_.func_74778_a("generatorName", this.field_76098_b.func_77127_a());
         p_76064_1_.func_74768_a("generatorVersion", this.field_76098_b.func_77131_c());
@@ -807,6 +809,26 @@
         });
     }
 
+    /**
+     * Allow access to additional mod specific world based properties
+     * Used by FML to store mod list associated with a world, and maybe an id map
+     * Used by Forge to store the dimensions available to a world
+     * @param additionalProperties
+     */
+    public void setAdditionalProperties(java.util.Map<String,net.minecraft.nbt.NBTBase> additionalProperties)
+    {
+        // one time set for this
+        if (this.additionalProperties == null)
+        {
+            this.additionalProperties = additionalProperties;
+        }
+    }
+
+    public net.minecraft.nbt.NBTBase getAdditionalProperty(String additionalProperty)
+    {
+        return this.additionalProperties!=null? this.additionalProperties.get(additionalProperty) : null;
+    }
+
     public NBTTagCompound func_186347_a(DimensionType p_186347_1_)
     {
         NBTTagCompound nbttagcompound = (NBTTagCompound)this.field_186348_N.get(p_186347_1_);