diff --git a/source/simulation2/components/CCmpFootprint.cpp b/source/simulation2/components/CCmpFootprint.cpp
index 3c99f60368..67cdd9ae76 100644
--- a/source/simulation2/components/CCmpFootprint.cpp
+++ b/source/simulation2/components/CCmpFootprint.cpp
@@ -59,15 +59,21 @@ public:
 			"<choice>"
 				"<element name='Square' a:help='Set the footprint to a square of the given size'>"
 					"<attribute name='width' a:help='Size of the footprint along the left/right direction (in metres)'>"
-						"<ref name='positiveDecimal'/>"
+						"<data type='decimal'>"
+							"<param name='minExclusive'>0.0</param>"
+						"</data>"
 					"</attribute>"
 					"<attribute name='depth' a:help='Size of the footprint along the front/back direction (in metres)'>"
-						"<ref name='positiveDecimal'/>"
+						"<data type='decimal'>"
+							"<param name='minExclusive'>0.0</param>"
+						"</data>"
 					"</attribute>"
 				"</element>"
 				"<element name='Circle' a:help='Set the footprint to a circle of the given size'>"
 					"<attribute name='radius' a:help='Radius of the footprint (in metres)'>"
-						"<ref name='positiveDecimal'/>"
+						"<data type='decimal'>"
+							"<param name='minExclusive'>0.0</param>"
+						"</data>"
 					"</attribute>"
 				"</element>"
 			"</choice>"
diff --git a/source/simulation2/components/CCmpVisualActor.cpp b/source/simulation2/components/CCmpVisualActor.cpp
index 0beb2d0d36..b1e3ac3c80 100644
--- a/source/simulation2/components/CCmpVisualActor.cpp
+++ b/source/simulation2/components/CCmpVisualActor.cpp
@@ -146,21 +146,31 @@ public:
 						"</element>"
 						"<element name='Box' a:help='Sets the selection shape to a box of specified dimensions'>"
 							"<attribute name='width'>"
-								"<ref name='positiveDecimal' />"
+								"<data type='decimal'>"
+									"<param name='minExclusive'>0.0</param>"
+								"</data>"
 							"</attribute>"
 							"<attribute name='height'>"
-								"<ref name='positiveDecimal' />"
+								"<data type='decimal'>"
+									"<param name='minExclusive'>0.0</param>"
+								"</data>"
 							"</attribute>"
 							"<attribute name='depth'>"
-								"<ref name='positiveDecimal' />"
+								"<data type='decimal'>"
+									"<param name='minExclusive'>0.0</param>"
+								"</data>"
 							"</attribute>"
 						"</element>"
 						"<element name='Cylinder' a:help='Sets the selection shape to a cylinder of specified dimensions'>"
 							"<attribute name='radius'>"
-								"<ref name='positiveDecimal' />"
+								"<data type='decimal'>"
+									"<param name='minExclusive'>0.0</param>"
+								"</data>"
 							"</attribute>"
 							"<attribute name='height'>"
-								"<ref name='positiveDecimal' />"
+								"<data type='decimal'>"
+									"<param name='minExclusive'>0.0</param>"
+								"</data>"
 							"</attribute>"
 						"</element>"
 					"</choice>"
diff --git a/source/simulation2/docs/SimulationDocs.h b/source/simulation2/docs/SimulationDocs.h
index dd64f8b56e..8066e687ec 100644
--- a/source/simulation2/docs/SimulationDocs.h
+++ b/source/simulation2/docs/SimulationDocs.h
@@ -298,12 +298,39 @@ The content will typically be one of:
 - <code>&lt;text/></code>
 - <code>&lt;data type='boolean'/></code>
 - <code>&lt;data type='decimal'/></code>
+- <code>&lt;data type='integer'/></code>
 - <code>&lt;data type='nonNegativeInteger'/></code>
 - <code>&lt;data type='positiveInteger'/></code>
+- <code>&lt;ref name='decimal'/></code>
 - <code>&lt;ref name='nonNegativeDecimal'/></code>
 - <code>&lt;ref name='positiveDecimal'/></code>
 
-(The last two are slightly different since they're not standard data types.)
+
+The <code>&lt;data&gt;</code> elements are native elements, while the <code>&lt;ref&gt;</code> elements are elements added for our engine. These non-native elements allow the definition of an operation that depends on the parent template. Possible operations are "add" and "mul", and can be applied as the example below.
+
+Say the parent template is
+@code 
+<Entity> 
+  <Example> 
+    <Name>Semi-Humanoids</Name> 
+    <Height>9000</Height> 
+    <Eyes/> 
+  </Example> 
+  <!-- ... other components ... --> 
+</Entity> 
+@endcode 
+and the child template appears like
+@code 
+<Entity> 
+  <Example> 
+    <Name>Barney</Name> 
+    <Height op="add">5</Height> 
+    <Eyes/> 
+  </Example> 
+  <!-- ... other components ... --> 
+</Entity> 
+@endcode 
+then Barney would have a height of 9005. 
 
 Elements can be wrapped in <code>&lt;optional></code>.
 Groups of elements can be wrapped in <code>&lt;choice></code> to allow only one of them.
diff --git a/source/simulation2/system/ComponentManager.cpp b/source/simulation2/system/ComponentManager.cpp
index 52a5203109..fb8e0383e4 100644
--- a/source/simulation2/system/ComponentManager.cpp
+++ b/source/simulation2/system/ComponentManager.cpp
@@ -1092,13 +1092,28 @@ void CComponentManager::SendGlobalMessage(entity_id_t ent, const CMessage& msg)
 
 std::string CComponentManager::GenerateSchema()
 {
+	std::string numericOperation =
+		"<optional>"
+			"<attribute name='op'>"
+				"<choice>"
+					"<value>add</value>"
+					"<value>mul</value>"
+				"</choice>"
+			"</attribute>"
+		"</optional>";
 	std::string schema =
 		"<grammar xmlns='http://relaxng.org/ns/structure/1.0' xmlns:a='http://ns.wildfiregames.com/entity' datatypeLibrary='http://www.w3.org/2001/XMLSchema-datatypes'>"
+			"<define name='decimal'>"
+				"<data type='decimal'/>"
+				+ numericOperation +
+			"</define>"
 			"<define name='nonNegativeDecimal'>"
 				"<data type='decimal'><param name='minInclusive'>0</param></data>"
+				+ numericOperation +
 			"</define>"
 			"<define name='positiveDecimal'>"
 				"<data type='decimal'><param name='minExclusive'>0</param></data>"
+				+ numericOperation +
 			"</define>"
 			"<define name='anything'>"
 				"<zeroOrMore>"
diff --git a/source/simulation2/system/ParamNode.cpp b/source/simulation2/system/ParamNode.cpp
index 53a661a2a4..c2fc414b6f 100644
--- a/source/simulation2/system/ParamNode.cpp
+++ b/source/simulation2/system/ParamNode.cpp
@@ -76,7 +76,13 @@ void CParamNode::ApplyLayer(const XMBFile& xmb, const XMBElement& element, const
 	// Look for special attributes
 	int at_disable = xmb.GetAttributeID("disable");
 	int at_replace = xmb.GetAttributeID("replace");
+	int at_op = xmb.GetAttributeID("op");
 	int at_datatype = xmb.GetAttributeID("datatype");
+	enum op {
+		INVALID,
+		ADD,
+		MUL
+	} op = INVALID;
 	bool replacing = false;
 	{
 		XERO_ITER_ATTR(element, attr)
@@ -91,6 +97,15 @@ void CParamNode::ApplyLayer(const XMBFile& xmb, const XMBElement& element, const
 				m_Childs.erase(name);
 				replacing = true;
 			}
+			else if (attr.Name == at_op)
+			{
+				if (std::wstring(attr.Value.begin(), attr.Value.end()) == L"add") 
+					op = ADD; 
+				else if (std::wstring(attr.Value.begin(), attr.Value.end()) == L"mul") 
+					op = MUL; 
+				else 
+					LOGWARNING("Invalid op '%ls'", attr.Value); 
+			}
 		}
 	}
 	{
@@ -137,6 +152,22 @@ void CParamNode::ApplyLayer(const XMBFile& xmb, const XMBElement& element, const
 
 	// Add this element as a child node
 	CParamNode& node = m_Childs[name];
+	if (op != INVALID) 
+	{ 
+		// TODO: Support parsing of data types other than fixed; log warnings in other cases
+		fixed oldval = node.ToFixed();
+		fixed mod = fixed::FromString(CStrW(value));
+		switch (op) 
+		{ 
+		case ADD: 
+			node.m_Value = (oldval + mod).ToString().FromUTF8(); 
+			break; 
+		case MUL: 
+			node.m_Value = (oldval.Multiply(mod)).ToString().FromUTF8(); 
+			break; 
+		} 
+		hasSetValue = true; 
+	} 
 	if (!hasSetValue)
 		node.m_Value = value;
 
@@ -150,7 +181,8 @@ void CParamNode::ApplyLayer(const XMBFile& xmb, const XMBElement& element, const
 	XERO_ITER_ATTR(element, attr)
 	{
 		// Skip special attributes
-		if (attr.Name == at_replace) continue;
+		if (attr.Name == at_replace || attr.Name == at_op)
+			continue;
 		// Add any others
 		std::string attrName = xmb.GetAttributeString(attr.Name);
 		node.m_Childs["@" + attrName].m_Value = attr.Value.FromUTF8();
diff --git a/source/tools/entity/Entity.pm b/source/tools/entity/Entity.pm
index bf4e66100a..5ac708f9bb 100644
--- a/source/tools/entity/Entity.pm
+++ b/source/tools/entity/Entity.pm
@@ -83,6 +83,19 @@ sub apply_layer
             }
         }
         $base->{' content'} = join ' ', @t;
+    } elsif ($new->{'@op'}) {
+        my $op = $new->{'@op'}{' content'};
+        my $op1 = $base->{' content'};
+        my $op2 = $new->{' content'};
+        if ($op eq 'add') {
+            $base->{' content'} = $op1 + $op2;
+        }
+        elsif ($op eq 'mul') {
+            $base->{' content'} = $op1 * $op2;
+        }
+        else {
+            die "Invalid operator '$op'";
+        }
     } else {
         $base->{' content'} = $new->{' content'};
     }
diff --git a/source/tools/templatesanalyzer/unitTables.py b/source/tools/templatesanalyzer/unitTables.py
index 916d616f5f..e7ab7fa59b 100644
--- a/source/tools/templatesanalyzer/unitTables.py
+++ b/source/tools/templatesanalyzer/unitTables.py
@@ -1,8 +1,27 @@
+# Copyright (c) 2015 Wildfire Games
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+# 
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
 import xml.etree.ElementTree as ET
 import os
 import glob
 
-# What data to use
 AttackTypes = ["Hack","Pierce","Crush"]
 Resources = ["food", "wood", "stone", "metal"]
 
@@ -17,7 +36,7 @@ LoadTemplatesIfParent = ["template_unit_infantry.xml", "template_unit_cavalry.xm
 Civs = ["athen", "mace", "spart", "sele", "cart", "rome", "pers", "maur", "brit", "gaul", "iber"]
 
 # Remote Civ templates with those strings in their name.
-FilterOut = ["marian"]
+FilterOut = ["marian", "thureophoros", "thorakites", "kardakes"]
 
 # Sorting parameters for the "roster variety" table
 ComparativeSortByCav = True
@@ -58,12 +77,26 @@ def hasParentTemplate(UnitName, parentName):
 
 	return False
 
+def NumericStatProcess(unitValue, templateValue):
+   	if not "op" in templateValue.attrib:
+   		return float(templateValue.text)
+	if (templateValue.attrib["op"] == "add"):
+		unitValue += float(templateValue.text)
+	elif (templateValue.attrib["op"] == "sub"):
+		unitValue -= float(templateValue.text)
+	elif (templateValue.attrib["op"] == "mul"):
+		unitValue *= float(templateValue.text)
+	elif (templateValue.attrib["op"] == "div"):
+		unitValue /= float(templateValue.text)
+	return unitValue
+
+
 # This function parses the entity values manually.
 def CalcUnit(UnitName, existingUnit = None):
 	unit = { 'HP' : "0", "BuildTime" : "0", "Cost" : { 'food' : "0", "wood" : "0", "stone" : "0", "metal" : "0", "population" : "0"},
 	'Attack' : { "Melee" : { "Hack" : 0, "Pierce" : 0, "Crush" : 0 }, "Ranged" : { "Hack" : 0, "Pierce" : 0, "Crush" : 0 } },
-	'RepeatRate' : {"Melee" : "0", "Ranged" : "0"},'PrepRate' : {"Melee" : "0", "Ranged" : "0"}, "Armour" : {},
-	"Ranged" : False, "Classes" : [], "AttackBonuses" : {}, "Restricted" : [],
+	'RepeatRate' : {"Melee" : "0", "Ranged" : "0"},'PrepRate' : {"Melee" : "0", "Ranged" : "0"}, "Armour" : { "Hack" : 0, "Pierce" : 0, "Crush" : 0},
+	"Ranged" : False, "Classes" : [], "AttackBonuses" : {}, "Restricted" : [], "WalkSpeed" : 0, "Range" : 0, "Spread" : 0,
 	"Civ" : None }
 	
 	if (existingUnit != None):
@@ -80,26 +113,26 @@ def CalcUnit(UnitName, existingUnit = None):
 		unit['Civ'] = Template.find("./Identity/Civ").text
 
 	if (Template.find("./Health/Max") != None):
-		unit['HP'] = Template.find("./Health/Max").text
+		unit['HP'] = NumericStatProcess(unit['HP'], Template.find("./Health/Max"))
 
 	if (Template.find("./Cost/BuildTime") != None):
-		unit['BuildTime'] = Template.find("./Cost/BuildTime").text
+		unit['BuildTime'] = NumericStatProcess(unit['BuildTime'], Template.find("./Cost/BuildTime"))
 	
 	if (Template.find("./Cost/Resources") != None):
 		for type in list(Template.find("./Cost/Resources")):
-			unit['Cost'][type.tag] = type.text
+			unit['Cost'][type.tag] = NumericStatProcess(unit['Cost'][type.tag], type)
 
 	if (Template.find("./Cost/Population") != None):
-		unit['Cost']["population"] = Template.find("./Cost/Population").text
+		unit['Cost']["population"] = NumericStatProcess(unit['Cost']["population"], Template.find("./Cost/Population"))
 
 	if (Template.find("./Attack/Melee") != None):
 		if (Template.find("./Attack/Melee/RepeatTime") != None):
-			unit['RepeatRate']["Melee"] = Template.find("./Attack/Melee/RepeatTime").text
+			unit['RepeatRate']["Melee"] = NumericStatProcess(unit['RepeatRate']["Melee"], Template.find("./Attack/Melee/RepeatTime"))
 		if (Template.find("./Attack/Melee/PrepareTime") != None):
-			unit['PrepRate']["Melee"] = Template.find("./Attack/Melee/PrepareTime").text
+			unit['PrepRate']["Melee"] = NumericStatProcess(unit['PrepRate']["Melee"], Template.find("./Attack/Melee/PrepareTime"))
 		for atttype in AttackTypes:
 			if (Template.find("./Attack/Melee/"+atttype) != None):
-				unit['Attack']['Melee'][atttype] = Template.find("./Attack/Melee/"+atttype).text
+				unit['Attack']['Melee'][atttype] = NumericStatProcess(unit['Attack']['Melee'][atttype], Template.find("./Attack/Melee/"+atttype))
 		if (Template.find("./Attack/Melee/Bonuses") != None):
 			for Bonus in Template.find("./Attack/Melee/Bonuses"):
 				Against = []
@@ -123,16 +156,16 @@ def CalcUnit(UnitName, existingUnit = None):
 	if (Template.find("./Attack/Ranged") != None):
 		unit['Ranged'] = True
 		if (Template.find("./Attack/Ranged/MaxRange") != None):
-			unit['Range'] = Template.find("./Attack/Ranged/MaxRange").text
+			unit['Range'] = NumericStatProcess(unit['Range'], Template.find("./Attack/Ranged/MaxRange"))
 		if (Template.find("./Attack/Ranged/Spread") != None):
-			unit['Spread'] = Template.find("./Attack/Ranged/Spread").text
+			unit['Spread'] = NumericStatProcess(unit['Spread'], Template.find("./Attack/Ranged/Spread"))
 		if (Template.find("./Attack/Ranged/RepeatTime") != None):
-			unit['RepeatRate']["Ranged"] = Template.find("./Attack/Ranged/RepeatTime").text
+			unit['RepeatRate']["Ranged"] = NumericStatProcess(unit['RepeatRate']["Ranged"], Template.find("./Attack/Ranged/RepeatTime"))
 		if (Template.find("./Attack/Ranged/PrepareTime") != None):
-			unit['PrepRate']["Ranged"] = Template.find("./Attack/Ranged/PrepareTime").text
+			unit['PrepRate']["Ranged"] = NumericStatProcess(unit['PrepRate']["Ranged"], Template.find("./Attack/Ranged/PrepareTime"))
 		for atttype in AttackTypes:
 			if (Template.find("./Attack/Ranged/"+atttype) != None):
-				unit['Attack']['Ranged'][atttype] = Template.find("./Attack/Ranged/"+atttype).text
+				unit['Attack']['Ranged'][atttype] = NumericStatProcess(unit['Attack']['Ranged'][atttype], Template.find("./Attack/Ranged/"+atttype))
 		if (Template.find("./Attack/Ranged/Bonuses") != None):
 			for Bonus in Template.find("./Attack/Ranged/Bonuses"):
 				Against = []
@@ -155,11 +188,11 @@ def CalcUnit(UnitName, existingUnit = None):
 	if (Template.find("./Armour") != None):
 		for atttype in AttackTypes:
 			if (Template.find("./Armour/"+atttype) != None):
-				unit['Armour'][atttype] = Template.find("./Armour/"+atttype).text
+				unit['Armour'][atttype] = NumericStatProcess(unit['Armour'][atttype], Template.find("./Armour/"+atttype))
 
 	if (Template.find("./UnitMotion") != None):
 		if (Template.find("./UnitMotion/WalkSpeed") != None):
-				unit['WalkSpeed'] = Template.find("./UnitMotion/WalkSpeed").text
+				unit['WalkSpeed'] = NumericStatProcess(unit['WalkSpeed'], Template.find("./UnitMotion/WalkSpeed"))
 
 	if (Template.find("./Identity/VisibleClasses") != None):
 		newClasses = Template.find("./Identity/VisibleClasses").text.split(" ")
@@ -209,7 +242,7 @@ def WriteUnit(Name, UnitDict):
 			ret += "<td> - </td>"
 		ret += "<td> - </td>"
 
-	if UnitDict["Ranged"] == True:
+	if UnitDict["Ranged"] == True and UnitDict["Range"] > 0:
 		ret += "<td>" + str("%.1f" % float(UnitDict["Range"])) + "</td>"
 		spread = (float(UnitDict["Spread"]) / float(UnitDict["Range"]))*100.0
 		ret += "<td>" + str("%.1f" % spread) + "</td>"