diff --git a/doc/assets/bookdata.graphml b/doc/assets/bookdata.graphml
index e60ad73c..a1722780 100644
--- a/doc/assets/bookdata.graphml
+++ b/doc/assets/bookdata.graphml
@@ -121,15 +121,15 @@ chapters<y:LabelModel>
     <node id="n7">
       <data key="d6">
         <y:GenericNode configuration="com.yworks.entityRelationship.big_entity">
-          <y:Geometry height="113.0" width="80.0" x="110.0" y="257.0"/>
+          <y:Geometry height="119.0" width="128.0" x="89.0" y="257.0"/>
           <y:Fill color="#E8EEF7" color2="#B7C9E3" transparent="false"/>
           <y:BorderStyle color="#000000" type="line" width="1.0"/>
-          <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="72.3671875" x="3.81640625" y="4.0">BookConfig</y:NodeLabel>
-          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="73.84375" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="58.169921875" x="2.0" y="29.96875">root
-src
-dest
-template
-renderer<y:LabelModel>
+          <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="72.3671875" x="27.81640625" y="4.0">BookConfig</y:NodeLabel>
+          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="73.84375" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="91.451171875" x="2.0" y="29.96875">lang
+project_root
+book_dest
+book_src
+template_path<y:LabelModel>
               <y:ErdAttributesNodeLabelModel/>
             </y:LabelModel>
             <y:ModelParameter>
@@ -145,12 +145,13 @@ renderer<y:LabelModel>
     <node id="n8">
       <data key="d6">
         <y:GenericNode configuration="com.yworks.entityRelationship.big_entity">
-          <y:Geometry height="75.0" width="80.0" x="464.36587981973474" y="414.2175368139224"/>
+          <y:Geometry height="90.0" width="80.0" x="357.375" y="414.2175368139224"/>
           <y:Fill color="#E8EEF7" color2="#B7C9E3" transparent="false"/>
           <y:BorderStyle color="#000000" type="line" width="1.0"/>
           <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="33.865234375" x="23.0673828125" y="4.0">Book</y:NodeLabel>
-          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="31.9375" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="62.16015625" x="2.0" y="29.96875">metadata
-chapters<y:LabelModel>
+          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="45.90625" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="62.16015625" x="2.0" y="29.96875">config
+metadata
+toc<y:LabelModel>
               <y:ErdAttributesNodeLabelModel/>
             </y:LabelModel>
             <y:ModelParameter>
@@ -170,7 +171,7 @@ chapters<y:LabelModel>
           <y:Fill color="#E8EEF7" color2="#B7C9E3" transparent="false"/>
           <y:BorderStyle color="#000000" type="line" width="1.0"/>
           <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="59.576171875" x="37.41191406249999" y="4.0">Renderer</y:NodeLabel>
-          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="126.818359375" x="2.0" y="29.96875">render(book, config)<y:LabelModel>
+          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="82.46875" x="2.0" y="29.96875">render(book)<y:LabelModel>
               <y:ErdAttributesNodeLabelModel/>
             </y:LabelModel>
             <y:ModelParameter>
@@ -186,12 +187,13 @@ chapters<y:LabelModel>
     <node id="n10">
       <data key="d6">
         <y:GenericNode configuration="com.yworks.entityRelationship.big_entity">
-          <y:Geometry height="90.0" width="80.0" x="336.4073791503906" y="414.2175368139224"/>
+          <y:Geometry height="90.0" width="91.0" x="2.594879150390625" y="443.7175368139224"/>
           <y:Fill color="#E8EEF7" color2="#B7C9E3" transparent="false"/>
           <y:BorderStyle color="#000000" type="line" width="1.0"/>
-          <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="53.458984375" x="13.2705078125" y="4.0">MDBook</y:NodeLabel>
-          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="31.9375" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="40.720703125" x="2.0" y="29.96875">books
-config<y:LabelModel>
+          <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="53.458984375" x="18.7705078125" y="4.0">MDBook</y:NodeLabel>
+          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="45.90625" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="76.234375" x="2.0" y="29.96875">project_root
+books
+renderer<y:LabelModel>
               <y:ErdAttributesNodeLabelModel/>
             </y:LabelModel>
             <y:ModelParameter>
@@ -223,7 +225,7 @@ config<y:LabelModel>
     <node id="n12">
       <data key="d6">
         <y:GenericNode configuration="com.yworks.entityRelationship.big_entity">
-          <y:Geometry height="90.0" width="105.0" x="376.0" y="257.5"/>
+          <y:Geometry height="90.0" width="105.0" x="344.875" y="257.5"/>
           <y:Fill color="#E8EEF7" color2="#B7C9E3" transparent="false"/>
           <y:BorderStyle color="#000000" type="line" width="1.0"/>
           <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="90.689453125" x="7.1552734375" y="4.0">BookMetadata</y:NodeLabel>
@@ -245,13 +247,12 @@ publisher<y:LabelModel>
     <node id="n13">
       <data key="d6">
         <y:GenericNode configuration="com.yworks.entityRelationship.big_entity">
-          <y:Geometry height="90.0" width="115.0" x="511.0" y="257.5"/>
+          <y:Geometry height="90.0" width="115.0" x="697.8658798197348" y="369.75"/>
           <y:Fill color="#E8EEF7" color2="#B7C9E3" transparent="false"/>
           <y:BorderStyle color="#000000" type="line" width="1.0"/>
           <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="94.275390625" x="10.3623046875" y="4.0">Vec&lt;Chapter&gt;</y:NodeLabel>
-          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="45.90625" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="83.921875" x="2.0" y="29.96875">title
-file
-sub_chapters<y:LabelModel>
+          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="31.9375" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="27.4609375" x="2.0" y="29.96875">title
+file<y:LabelModel>
               <y:ErdAttributesNodeLabelModel/>
             </y:LabelModel>
             <y:ModelParameter>
@@ -281,6 +282,48 @@ sub_chapters<y:LabelModel>
         </y:GenericNode>
       </data>
     </node>
+    <node id="n15">
+      <data key="d4"/>
+      <data key="d5"/>
+      <data key="d6">
+        <y:ShapeNode>
+          <y:Geometry height="50.0" width="110.0" x="520.0" y="257.5"/>
+          <y:Fill color="#FFCC00" transparent="false"/>
+          <y:BorderStyle color="#000000" type="line" width="1.0"/>
+          <y:NodeLabel alignment="center" autoSizePolicy="content" fontFamily="Dialog" fontSize="13" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="34.265625" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="bottom" visible="true" width="65.34375" x="22.328125" y="7.8671875">summary
+parser<y:LabelModel>
+              <y:SmartNodeLabelModel distance="4.0"/>
+            </y:LabelModel>
+            <y:ModelParameter>
+              <y:SmartNodeLabelModelParameter labelRatioX="0.0" labelRatioY="0.0" nodeRatioX="0.0" nodeRatioY="0.0" offsetX="0.0" offsetY="0.0" upX="0.0" upY="-1.0"/>
+            </y:ModelParameter>
+          </y:NodeLabel>
+          <y:Shape type="ellipse"/>
+        </y:ShapeNode>
+      </data>
+    </node>
+    <node id="n16">
+      <data key="d5"/>
+      <data key="d6">
+        <y:GenericNode configuration="com.yworks.entityRelationship.big_entity">
+          <y:Geometry height="90.0" width="115.0" x="515.0" y="369.75"/>
+          <y:Fill color="#E8EEF7" color2="#B7C9E3" transparent="false"/>
+          <y:BorderStyle color="#000000" type="line" width="1.0"/>
+          <y:NodeLabel alignment="center" autoSizePolicy="content" backgroundColor="#B7C9E3" configuration="com.yworks.entityRelationship.label.name" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="internal" modelPosition="t" textColor="#000000" verticalTextPosition="bottom" visible="true" width="94.884765625" x="10.0576171875" y="4.0">Vec&lt;TocItem&gt;</y:NodeLabel>
+          <y:NodeLabel alignment="left" autoSizePolicy="content" configuration="com.yworks.entityRelationship.label.attributes" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="31.9375" horizontalTextPosition="center" iconTextGap="4" modelName="custom" textColor="#000000" verticalTextPosition="top" visible="true" width="64.837890625" x="2.0" y="29.96875">content
+sub_items<y:LabelModel>
+              <y:ErdAttributesNodeLabelModel/>
+            </y:LabelModel>
+            <y:ModelParameter>
+              <y:ErdAttributesNodeLabelModelParameter/>
+            </y:ModelParameter>
+          </y:NodeLabel>
+          <y:StyleProperties>
+            <y:Property class="java.lang.Boolean" name="y.view.ShadowNodePainter.SHADOW_PAINTING" value="true"/>
+          </y:StyleProperties>
+        </y:GenericNode>
+      </data>
+    </node>
     <edge id="e0" source="n4" target="n4">
       <data key="d10">
         <y:ArcEdge>
@@ -296,29 +339,29 @@ sub_chapters<y:LabelModel>
     <edge id="e1" source="n2" target="n7">
       <data key="d10">
         <y:ArcEdge>
-          <y:Path sx="0.0" sy="0.0" tx="-0.5713348388671875" ty="-40.17777777777778">
-            <y:Point x="131.00865173339844" y="180.87705993652344"/>
+          <y:Path sx="0.0" sy="0.0" tx="-0.9141357421875003" ty="-42.31111111111111">
+            <y:Point x="132.33807373046875" y="181.30795288085938"/>
           </y:Path>
           <y:LineStyle color="#000000" type="line" width="1.0"/>
           <y:Arrows source="none" target="standard"/>
-          <y:EdgeLabel alignment="right" configuration="AutoFlippingLabel" distance="2.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="31.9375" horizontalTextPosition="center" iconTextGap="4" modelName="free" modelPosition="anywhere" preferredPlacement="left" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="125.921875" x="-113.5390319824219" y="92.04427337646476">behaviour control,
+          <y:EdgeLabel alignment="right" configuration="AutoFlippingLabel" distance="2.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="31.9375" horizontalTextPosition="center" iconTextGap="4" modelName="free" modelPosition="anywhere" preferredPlacement="left" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="125.921875" x="-112.17275522838912" y="92.57967131345038">behaviour control,
 paths, target format<y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRightSide="0" angleReference="absolute" angleRotationOnRightSide="co" distance="-1.0" placement="anywhere" side="left" sideReference="relative_to_edge_flow"/>
           </y:EdgeLabel>
-          <y:Arc height="0.17272590100765228" ratio="0.003664793446660042" type="fixedRatio"/>
+          <y:Arc height="0.17399874329566956" ratio="0.003664793446660042" type="fixedRatio"/>
         </y:ArcEdge>
       </data>
     </edge>
     <edge id="e2" source="n3" target="n7">
       <data key="d10">
         <y:ArcEdge>
-          <y:Path sx="0.0" sy="0.0" tx="13.85631193730191" ty="-56.48749113237591">
-            <y:Point x="191.57940673828125" y="167.03758239746094"/>
+          <y:Path sx="0.0" sy="0.0" tx="22.170099099683064" ty="-59.48682694471443">
+            <y:Point x="197.2362518310547" y="167.87789916992188"/>
           </y:Path>
           <y:LineStyle color="#000000" type="line" width="1.0"/>
           <y:Arrows source="none" target="standard"/>
-          <y:EdgeLabel alignment="left" configuration="AutoFlippingLabel" distance="1.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="free" modelPosition="anywhere" preferredPlacement="right" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="37.533203125" x="-43.598876953125" y="101.51483154296875">paths<y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRightSide="0" angleReference="absolute" angleRotationOnRightSide="co" distance="-1.0" placement="anywhere" side="right" sideReference="relative_to_edge_flow"/>
+          <y:EdgeLabel alignment="left" configuration="AutoFlippingLabel" distance="1.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="free" modelPosition="anywhere" preferredPlacement="right" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="37.533203125" x="-38.136329861917886" y="103.87263713435809">paths<y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRightSide="0" angleReference="absolute" angleRotationOnRightSide="co" distance="-1.0" placement="anywhere" side="right" sideReference="relative_to_edge_flow"/>
           </y:EdgeLabel>
-          <y:Arc height="-13.828213691711426" ratio="-0.29697197675704956" type="fixedRatio"/>
+          <y:Arc height="-13.487004280090332" ratio="-0.29697197675704956" type="fixedRatio"/>
         </y:ArcEdge>
       </data>
     </edge>
@@ -326,11 +369,11 @@ paths, target format<y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRig
       <data key="d10">
         <y:ArcEdge>
           <y:Path sx="0.0" sy="0.0" tx="0.0" ty="0.0">
-            <y:Point x="353.7525329589844" y="180.75323486328125"/>
+            <y:Point x="338.1900329589844" y="183.28660583496094"/>
           </y:Path>
           <y:LineStyle color="#000000" type="line" width="1.0"/>
           <y:Arrows source="none" target="standard"/>
-          <y:EdgeLabel alignment="center" configuration="AutoFlippingLabel" distance="2.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="custom" preferredPlacement="anywhere" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="62.16015625" x="18.158484098010604" y="77.33507585168667">metadata<y:LabelModel>
+          <y:EdgeLabel alignment="center" configuration="AutoFlippingLabel" distance="2.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="custom" preferredPlacement="anywhere" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="62.16015625" x="5.276900303809384" y="76.05124071206538">metadata<y:LabelModel>
               <y:SmartEdgeLabelModel autoRotationEnabled="false" defaultAngle="0.0" defaultDistance="10.0"/>
             </y:LabelModel>
             <y:ModelParameter>
@@ -338,68 +381,56 @@ paths, target format<y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRig
             </y:ModelParameter>
             <y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRightSide="0" angleReference="absolute" angleRotationOnRightSide="co" distance="-1.0" frozen="true" placement="anywhere" side="anywhere" sideReference="relative_to_edge_flow"/>
           </y:EdgeLabel>
-          <y:Arc height="22.95389747619629" ratio="0.32557427883148193" type="fixedRatio"/>
+          <y:Arc height="21.38491439819336" ratio="0.32557427883148193" type="fixedRatio"/>
         </y:ArcEdge>
       </data>
     </edge>
-    <edge id="e4" source="n4" target="n13">
+    <edge id="e4" source="n4" target="n15">
       <data key="d10">
         <y:ArcEdge>
           <y:Path sx="0.0" sy="0.0" tx="0.0" ty="0.0">
-            <y:Point x="509.19012451171875" y="186.79183959960938"/>
+            <y:Point x="511.2044982910156" y="176.3902587890625"/>
           </y:Path>
           <y:LineStyle color="#000000" type="line" width="1.0"/>
           <y:Arrows source="none" target="standard"/>
-          <y:EdgeLabel alignment="center" configuration="AutoFlippingLabel" distance="2.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="free" modelPosition="anywhere" preferredPlacement="anywhere" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="71.634765625" x="-12.16741943359375" y="74.53813934326172">chapter list<y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRightSide="0" angleReference="absolute" angleRotationOnRightSide="co" distance="-1.0" frozen="true" placement="anywhere" side="anywhere" sideReference="relative_to_edge_flow"/>
+          <y:EdgeLabel alignment="center" configuration="AutoFlippingLabel" distance="2.0" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" height="17.96875" horizontalTextPosition="center" iconTextGap="4" modelName="free" modelPosition="anywhere" preferredPlacement="anywhere" ratio="0.5" textColor="#000000" verticalTextPosition="bottom" visible="true" width="71.634765625" x="-8.507094384363711" y="70.80742538314036">chapter list<y:PreferredPlacementDescriptor angle="0.0" angleOffsetOnRightSide="0" angleReference="absolute" angleRotationOnRightSide="co" distance="-1.0" frozen="true" placement="anywhere" side="anywhere" sideReference="relative_to_edge_flow"/>
           </y:EdgeLabel>
-          <y:Arc height="15.944525718688965" ratio="0.2471216768026352" type="fixedRatio"/>
+          <y:Arc height="15.182718276977539" ratio="0.2471216768026352" type="fixedRatio"/>
         </y:ArcEdge>
       </data>
     </edge>
-    <edge id="e5" source="n5" target="n13">
+    <edge id="e5" source="n5" target="n15">
       <data key="d10">
         <y:ArcEdge>
           <y:Path sx="0.0" sy="0.0" tx="0.0" ty="0.0">
-            <y:Point x="599.7504272460938" y="197.5275421142578"/>
+            <y:Point x="600.8458251953125" y="186.82730102539062"/>
           </y:Path>
           <y:LineStyle color="#000000" type="line" width="1.0"/>
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diff --git a/doc/assets/bookdata.png b/doc/assets/bookdata.png
index bcab50dc..f206399a 100644
Binary files a/doc/assets/bookdata.png and b/doc/assets/bookdata.png differ
diff --git a/doc/assets/structs-reorganized.png b/doc/assets/structs-reorganized.png
new file mode 100644
index 00000000..cd33bb9c
Binary files /dev/null and b/doc/assets/structs-reorganized.png differ
diff --git a/doc/assets/structs-reorganized.pum b/doc/assets/structs-reorganized.pum
new file mode 100644
index 00000000..6dc4de93
--- /dev/null
+++ b/doc/assets/structs-reorganized.pum
@@ -0,0 +1,129 @@
+@startuml
+
+class book::MDBook {
+  project_root : PathBuf
+
+  books : HashMap<&'a str, Book>
+
+  renderer : Box<Renderer>
+  livereload : Option<String>
+  indent_spaces: i32
+  multilingual: bool
+
+  new(root)
+}
+
+class book::book.Book {
+  config : BookConfig
+  metadata : BookMetadata
+
+  chapters: Vec<Chapter>
+
+  new(title)
+}
+
+class book::bookconfig.BookConfig {
+  lang : Language
+
+  project_root : PathBuf
+  book_dest : PathBuf
+  book_src : PathBuf
+  template_path : PathBuf
+
+  new(root)
+}
+
+class book::chapter.Chapter {
+title
+file
+author
+description
+css_class
+index : Vec<i32>
+
+new(title, file)
+}
+
+namespace book::toc {
+
+class TocItem {
+  content : TocContent
+  sub_items: Vec<TocItem>
+  new(content)
+}
+
+enum TocContent {
+  Frontmatter "Chapter"
+  Mainmatter "Chapter"
+  Backmatter "Chapter"
+  Insert "Chapter"
+  Spacer
+}
+
+}
+
+namespace book::metadata {
+
+class BookMetadata {
+  title
+  subtitle
+  description
+  publisher
+  language
+  authors
+  translators
+  number_format
+  section_names
+  new(title)
+}
+
+class Author {
+  name
+  email
+  new(name)
+}
+
+class Language {
+  name
+  code
+}
+
+class Publisher {
+  name
+  url
+  logo_src
+}
+
+enum NumberFormat {
+  Arabic
+  Roman
+  Word
+}
+
+}
+
+class renderer::html_handlebars::HtmlHandlebars {
+  new()
+  render(book: MDBook)
+}
+
+class theme::Theme {
+  index
+  css
+  favicon
+  js
+  highlight_css
+  tomorrow_night_css
+  highlight_js
+  jquery
+  new(src)
+}
+
+book::book-[hidden]->book::bookconfig
+book::book-[hidden]->book::chapter
+book::book-[hidden]->book::toc
+book::book-[hidden]->book::metadata
+
+renderer::html_handlebars::HtmlHandlebars-[hidden]->theme::Theme
+
+@enduml
diff --git a/doc/doc.md b/doc/doc.md
index 27ae47a5..961f4926 100644
--- a/doc/doc.md
+++ b/doc/doc.md
@@ -1,17 +1,38 @@
 # Doc
 
-Diagrams are with [yEd](http://www.yworks.com/products/yed) and [plantuml](http://plantuml.com).
+Diagrams are with [yEd](http://www.yworks.com/products/yed)
+and [plantuml](http://plantuml.com).
 
 ## Data
 
+`MDBook::new(root)` parses CLI args and `book.toml` to create:
+
+- app config settings
+- `Book` for each language
+
+Each `Book` is given their config setting with their source- and destination
+paths.
+
+The renderer can then render each book.
+
+To render the TOC, renderer gets a Vec<TocItem> from summary parser.
+
+The renderer walks through the Vec. It can match content kinds in an enum and
+this way knows whether to render:
+
+- front- back- or mainmatter
+- spacer elements (vertical space in TOC but no chapter output)
+- insert chapters (no TOC link, but the chapter is part of the reading sequence)
+
 ![book data](assets/bookdata.png)
 
 ### Renderer
 
-Takes data from:
+Takes a book, which knows:
 
-- a book's metadata and chapters (`Book`)
-- paths and behaviour config (`BookConfig`)
+- metadata
+- toc with chapters
+- config for paths
 - template assets (`template_path`)
 
 For generating pages:
@@ -22,7 +43,8 @@ those properties which can be easily anticipated.
 If Renderer needs more specific data, it can be supplied in `book.toml`. It's
 the Renderer's job to open that and parse it out.
 
-Chapters, `Vec<Chapter>`.
+Chapters are represented in a `Vec<TocItem>`, each item has the chapter content
+as payload.
 
 If the user wants to store attributes that are not anticipated with structs,
 they can go in a hashmap with string keys, let them be accessible from the
@@ -41,26 +63,20 @@ renderer.
 Takes data from:
 
 - CLI args
-- book.json
+- book.toml
 
 ## Structs
 
+### Reorganized
+
+![structs reorganized](assets/structs-reorganized.png)
+
 ### Currently
 
-Already almost good for implementing the above.
-
-Storing data attributes can be reorganized.
-
-Modules could be refactored to express intention more clearly.
-
 ![structs](assets/structs.png)
 
 ## Notes
 
-There could be less modules. Merge modules which express one intention.
-
-The two Chapter structs could be refactored out.
-
 Take config paths for as many things as possible. Let the user organize their
 project folder differently, or allow `mdbook` to function in existing projects
 with already established folders.