diff --git a/include/etl/fsm.h b/include/etl/fsm.h
index 6123539b..2f71d587 100644
--- a/include/etl/fsm.h
+++ b/include/etl/fsm.h
@@ -195,6 +195,7 @@ namespace etl
 
     //*******************************************
     /// Adds a child to this state.
+    /// Only of use when part of an HFSM.
     //*******************************************
     void add_child_state(etl::ifsm_state& state)
     {
@@ -210,6 +211,7 @@ namespace etl
 
     //*******************************************
     /// Adds a list of child states.
+    /// Only of use when part of an HFSM.
     //*******************************************
     template <typename TSize>
     void set_child_states(etl::ifsm_state** state_list, TSize size)
@@ -224,30 +226,6 @@ namespace etl
       }
     }
 
-    //*******************************************
-    /// Get the parent state for this state.
-    //*******************************************
-    etl::ifsm_state* get_parent_state() const
-    {
-      return p_parent;
-    }
-
-    //*******************************************
-    /// Get the active child state for this state.
-    //*******************************************
-    etl::ifsm_state* get_active_child_state() const
-    {
-      return p_active_child;
-    }
-
-    //*******************************************
-    /// Get the default child state for this state.
-    //*******************************************
-    etl::ifsm_state* get_default_child_state() const
-    {
-      return p_default_child;
-    }
-
   protected:
 
     //*******************************************
diff --git a/include/etl/hfsm.h b/include/etl/hfsm.h
index 134f18d1..deb233ff 100644
--- a/include/etl/hfsm.h
+++ b/include/etl/hfsm.h
@@ -5,7 +5,7 @@ Embedded Template Library.
 https://github.com/ETLCPP/etl
 https://www.etlcpp.com
 
-Copyright(c) 2021
+Copyright(c) 2021 Jeremy Overesch, John Wellbelove
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files(the "Software"), to deal
@@ -88,41 +88,41 @@ namespace etl
     //*******************************************
     /// Return the first common ancester of the two states.
     //*******************************************
-    static etl::ifsm_state* common_ancestor(etl::ifsm_state* p1, etl::ifsm_state* p2)
+    static etl::ifsm_state* common_ancestor(etl::ifsm_state* s1, etl::ifsm_state* s2)
     {
-      size_t depth1 = get_depth(p1);
-      size_t depth2 = get_depth(p2);
+      size_t depth1 = get_depth(s1);
+      size_t depth2 = get_depth(s2);
 
-      // Adjust p1 and p2 to the same depth.
+      // Adjust s1 and s2 to the same depth.
       if (depth1 > depth2)
       {
-        p1 = adjust_depth(p1, depth1 - depth2);
+        s1 = adjust_depth(s1, depth1 - depth2);
       }
       else
       {
-        p2 = adjust_depth(p2, depth2 - depth1);
+        s2 = adjust_depth(s2, depth2 - depth1);
       }
 
       // Now they're aligned to the same depth they can step towards the root together.
-      while (p1 != p2)
+      while (s1 != s2)
       {
-        p1 = p1->p_parent;
-        p2 = p2->p_parent;
+        s1 = s1->p_parent;
+        s2 = s2->p_parent;
       }
 
-      return p1;
+      return s1;
     }
 
     //*******************************************
     /// Find the depth of the state.
     //*******************************************
-    static size_t get_depth(etl::ifsm_state* p)
+    static size_t get_depth(etl::ifsm_state* s)
     {
       size_t depth = 0;
 
-      while (p != ETL_NULLPTR)
+      while (s != ETL_NULLPTR)
       {
-        p = p->p_parent;
+        s = s->p_parent;
         ++depth;
       }
 
@@ -132,15 +132,15 @@ namespace etl
     //*******************************************
     /// Align the depths of the states.
     //*******************************************
-    static etl::ifsm_state* adjust_depth(etl::ifsm_state* p, size_t offset)
+    static etl::ifsm_state* adjust_depth(etl::ifsm_state* s, size_t offset)
     {
       while (offset != 0U)
       {
-        p = p->p_parent;
+        s = s->p_parent;
         --offset;
       }
 
-      return p;
+      return s;
     }
 
     //*******************************************
diff --git a/include/etl/version.h b/include/etl/version.h
index b80198b3..5a95ecd8 100644
--- a/include/etl/version.h
+++ b/include/etl/version.h
@@ -38,8 +38,8 @@ SOFTWARE.
 ///\ingroup utilities
 
 #define ETL_VERSION_MAJOR 20
-#define ETL_VERSION_MINOR  9
-#define ETL_VERSION_PATCH  3
+#define ETL_VERSION_MINOR 10
+#define ETL_VERSION_PATCH  0
 #define ETL_VERSION       ETL_STRINGIFY(ETL_VERSION_MAJOR) "." ETL_STRINGIFY(ETL_VERSION_MINOR) "." ETL_STRINGIFY(ETL_VERSION_PATCH)
 #define ETL_VERSION_W     ETL_STRINGIFY(ETL_VERSION_MAJOR) L"." ETL_STRINGIFY(ETL_VERSION_MINOR) L"." ETL_STRINGIFY(ETL_VERSION_PATCH)
 #define ETL_VERSION_U16   ETL_STRINGIFY(ETL_VERSION_MAJOR) u"." ETL_STRINGIFY(ETL_VERSION_MINOR) u"." ETL_STRINGIFY(ETL_VERSION_PATCH)
diff --git a/library.json b/library.json
index ae9e5b9a..5f1e835b 100644
--- a/library.json
+++ b/library.json
@@ -1,6 +1,6 @@
 {
   "name": "ETL Embedded Template Library",
-  "version": "20.9.3",
+  "version": "20.10.0",
   "author s": {
     "name": "John Wellbelove",
     "email": "john.wellbelove@etlcpp.com"
diff --git a/library.properties b/library.properties
index 8b9d4db7..295d134a 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=Embedded Template Library ETL
-version=20.9.3
+version=20.10.0
 author= John Wellbelove <john.wellbelove@etlcpp.com>
 maintainer=John Wellbelove <john.wellbelove@etlcpp.com>
 license=MIT
diff --git a/support/Release notes.txt b/support/Release notes.txt
index f419d1b2..2d89550f 100644
--- a/support/Release notes.txt	
+++ b/support/Release notes.txt	
@@ -1,3 +1,7 @@
+===============================================================================
+20.10.0
+Added Hierarchical Finite State Machine (etl::hfsm) derived from etl::fsm
+
 ===============================================================================
 20.9.3
 Fixed misspelt DBL_MAX macro.