diff --git a/4-high/gel/source/world/gel-world.adb b/4-high/gel/source/world/gel-world.adb
index f92121c..40f83fd 100644
--- a/4-high/gel/source/world/gel-world.adb
+++ b/4-high/gel/source/world/gel-world.adb
@@ -1154,6 +1154,21 @@ is
 
 
 
+
+   -------
+   --- Ids
+   --
+
+   procedure reserve_Ids (Self : in out Item;   Before : in long_Integer)
+   is
+   begin
+      Self.last_used_sprite_Id        :=         sprite_Id (Before - 1);
+      Self.last_used_model_Id         := graphics_model_Id (Before - 1);
+      Self.last_used_physics_model_Id := physics .model_Id (Before - 1);
+   end reserve_Ids;
+
+
+
    -----------
    --  Testing
    --
diff --git a/4-high/gel/source/world/gel-world.ads b/4-high/gel/source/world/gel-world.ads
index 722159f..4b9b7f1 100644
--- a/4-high/gel/source/world/gel-world.ads
+++ b/4-high/gel/source/world/gel-world.ads
@@ -241,7 +241,6 @@ is
 
 
 
-
    --------------------
    ---  World Mirroring
    --
@@ -269,6 +268,7 @@ is
    function  Sprites         (Self : in out Item) return remote.World.sprite_model_Pairs;
 
 
+
    ----------
    --- Models
    --
@@ -297,6 +297,15 @@ is
 
 
 
+   -------
+   --- Ids
+   --
+
+   procedure reserve_Ids (Self : in out Item;   Before : in long_Integer);
+
+
+
+
    ------------------
    ---  Testing/Debug
    --
@@ -427,7 +436,7 @@ private
          --  Ids
          --
          last_used_sprite_Id        : gel.sprite_Id         := 0;
-         last_used_model_Id         : gel.graphics_model_Id := 0;
+         last_used_model_Id         : gel.graphics_model_Id := 0;     --TODO: Rename to 'last_used_graphics_model_Id'.
          last_used_physics_model_Id : physics     .model_Id := 0;
 
          --  Free Sets