diff --git a/interface/src/avatar/MyAvatar.cpp b/interface/src/avatar/MyAvatar.cpp
index ecfa848630..b50e550deb 100644
--- a/interface/src/avatar/MyAvatar.cpp
+++ b/interface/src/avatar/MyAvatar.cpp
@@ -1223,7 +1223,7 @@ void MyAvatar::setupNewAnimationSystem() {
     // create a blend node
     auto blend = make_shared<AnimBlendLinear>("blend", 0.5f);
     auto idle = make_shared<AnimClip>("clip", "https://hifi-public.s3.amazonaws.com/ozan/support/FightClubBotTest1/Animations/standard_idle.fbx", 0.0f, 90.0f, 1.0f, true);
-    auto walk = make_shared<AnimClip>("clip", "https://hifi-public.s3.amazonaws.com/ozan/support/FightClubBotTest1/Animations/standard_walk.fbx", 0.0f, 29.0f, 1.0f, true);
+    auto walk = make_shared<AnimClip>("clip", "https://hifi-public.s3.amazonaws.com/ozan/support/FightClubBotTest1/Animations/standard_walk.fbx", 0.0f, 28.0f, 1.0f, true);
     blend->addChild(idle);
     blend->addChild(walk);
     _animNode = blend;
diff --git a/libraries/animation/src/AnimBlendLinear.h b/libraries/animation/src/AnimBlendLinear.h
index db217a25ee..c1c1c928e5 100644
--- a/libraries/animation/src/AnimBlendLinear.h
+++ b/libraries/animation/src/AnimBlendLinear.h
@@ -12,6 +12,16 @@
 #ifndef hifi_AnimBlendLinear_h
 #define hifi_AnimBlendLinear_h
 
+// Linear blend between two AnimNodes.
+// the amount of blending is determined by the alpha parameter.
+// If the number of children is 2, then the alpha parameters should be between
+// 0 and 1.  The first animation will have a (1 - alpha) factor, and the second
+// will have factor of alpha.
+// This node supports more then 2 children.  In this case the alpha should be
+// between 0 and n - 1.  This alpha can be used to linearly interpolate between
+// the closest two children poses.  This can be used to sweep through a series
+// of animation poses.
+
 class AnimBlendLinear : public AnimNode {
 public:
 
diff --git a/libraries/animation/src/AnimClip.h b/libraries/animation/src/AnimClip.h
index 59b286b95f..1868ac0e03 100644
--- a/libraries/animation/src/AnimClip.h
+++ b/libraries/animation/src/AnimClip.h
@@ -14,6 +14,12 @@
 #include "AnimationCache.h"
 #include "AnimNode.h"
 
+// Playback a single animation timeline.
+// url determines the location of the fbx file to use within this clip.
+// startFrame and endFrame are in frames 1/30th of a second.
+// timescale can be used to speed-up or slow-down the animation.
+// loop flag, when true, will loop the animation as it reaches the end frame.
+
 class AnimClip : public AnimNode {
 public:
     friend class AnimClipTests;
diff --git a/libraries/animation/src/AnimNode.h b/libraries/animation/src/AnimNode.h
index 6ee7ff89c8..debc423e20 100644
--- a/libraries/animation/src/AnimNode.h
+++ b/libraries/animation/src/AnimNode.h
@@ -21,6 +21,15 @@
 
 class QJsonObject;
 
+// Base class for all elements in the animation blend tree.
+// It provides the following categories of functions:
+//
+//   * id getter, id is a string name useful for debugging and searching.
+//   * type getter, helpful for determining the derived type of this node.
+//   * hierarchy accessors, for adding, removing and iterating over child AnimNodes
+//   * skeleton accessors, the skeleton is from the model whose bones we are going to manipulate
+//   * evaluate method, perform actual joint manipulations here and return result by reference.
+
 class AnimNode {
 public:
     friend class AnimDebugDraw;
@@ -37,6 +46,7 @@ public:
     const std::string& getID() const { return _id; }
     Type getType() const { return _type; }
 
+    // hierarchy accessors
     void addChild(Pointer child) { _children.push_back(child); }
     void removeChild(Pointer child) {
         auto iter = std::find(_children.begin(), _children.end(), child);
@@ -62,6 +72,9 @@ public:
     virtual ~AnimNode() {}
 
     virtual const std::vector<AnimPose>& evaluate(float dt) = 0;
+    virtual const std::vector<AnimPose>& overlay(float dt, const std::vector<AnimPose>& underPoses) {
+        return evaluate(dt);
+    }
 
 protected: