diff --git a/OpenRA.Game/Traits/World/ActorMap.cs b/OpenRA.Game/Traits/World/ActorMap.cs
index b90a987052..f6b8dc4a1d 100644
--- a/OpenRA.Game/Traits/World/ActorMap.cs
+++ b/OpenRA.Game/Traits/World/ActorMap.cs
@@ -212,35 +212,36 @@ namespace OpenRA.Traits
 					yield return i.Actor;
 		}
 
-		public bool HasFreeSubCell(CPos a, bool checkTransient = true)
+		public bool HasFreeSubCell(CPos cell, bool checkTransient = true)
 		{
-			return FreeSubCell(a, SubCell.Any, checkTransient) != SubCell.Invalid;
+			return FreeSubCell(cell, SubCell.Any, checkTransient) != SubCell.Invalid;
 		}
 
-		public SubCell FreeSubCell(CPos a, SubCell preferredSubCell = SubCell.Any, bool checkTransient = true)
+		public SubCell FreeSubCell(CPos cell, SubCell preferredSubCell = SubCell.Any, bool checkTransient = true)
 		{
-			if (preferredSubCell > SubCell.Any && !AnyUnitsAt(a, preferredSubCell, checkTransient))
+			if (preferredSubCell > SubCell.Any && !AnyUnitsAt(cell, preferredSubCell, checkTransient))
 				return preferredSubCell;
 
-			if (!AnyUnitsAt(a))
+			if (!AnyUnitsAt(cell))
 				return map.DefaultSubCell;
 
 			for (var i = (int)SubCell.First; i < map.SubCellOffsets.Length; i++)
-				if (i != (int)preferredSubCell && !AnyUnitsAt(a, (SubCell)i, checkTransient))
+				if (i != (int)preferredSubCell && !AnyUnitsAt(cell, (SubCell)i, checkTransient))
 					return (SubCell)i;
+
 			return SubCell.Invalid;
 		}
 
-		public SubCell FreeSubCell(CPos a, SubCell preferredSubCell, Func<Actor, bool> checkIfBlocker)
+		public SubCell FreeSubCell(CPos cell, SubCell preferredSubCell, Func<Actor, bool> checkIfBlocker)
 		{
-			if (preferredSubCell > SubCell.Any && !AnyUnitsAt(a, preferredSubCell, checkIfBlocker))
+			if (preferredSubCell > SubCell.Any && !AnyUnitsAt(cell, preferredSubCell, checkIfBlocker))
 				return preferredSubCell;
 
-			if (!AnyUnitsAt(a))
+			if (!AnyUnitsAt(cell))
 				return map.DefaultSubCell;
 
 			for (var i = (int)SubCell.First; i < map.SubCellOffsets.Length; i++)
-				if (i != (int)preferredSubCell && !AnyUnitsAt(a, (SubCell)i, checkIfBlocker))
+				if (i != (int)preferredSubCell && !AnyUnitsAt(cell, (SubCell)i, checkIfBlocker))
 					return (SubCell)i;
 			return SubCell.Invalid;
 		}
@@ -325,7 +326,7 @@ namespace OpenRA.Traits
 			}
 		}
 
-		void RemoveInfluenceInner(ref InfluenceNode influenceNode, Actor toRemove)
+		static void RemoveInfluenceInner(ref InfluenceNode influenceNode, Actor toRemove)
 		{
 			if (influenceNode == null)
 				return;
diff --git a/OpenRA.Game/WPos.cs b/OpenRA.Game/WPos.cs
index 024e6ab4df..c1dfc4babc 100644
--- a/OpenRA.Game/WPos.cs
+++ b/OpenRA.Game/WPos.cs
@@ -35,6 +35,9 @@ namespace OpenRA
 		public static bool operator ==(WPos me, WPos other) { return me.X == other.X && me.Y == other.Y && me.Z == other.Z; }
 		public static bool operator !=(WPos me, WPos other) { return !(me == other); }
 
+		/// <summary>
+		/// Returns the linear interpolation between points 'a' and 'b'
+		/// </summary>
 		public static WPos Lerp(WPos a, WPos b, int mul, int div) { return a + (b - a) * mul / div; }
 
 		public static WPos LerpQuadratic(WPos a, WPos b, WAngle pitch, int mul, int div)