diff --git a/libraries/pbrlib/pbrlib_defs.mtlx b/libraries/pbrlib/pbrlib_defs.mtlx
index 1ac4df2590..a525e0a3f6 100644
--- a/libraries/pbrlib/pbrlib_defs.mtlx
+++ b/libraries/pbrlib/pbrlib_defs.mtlx
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materialx version="1.38">
   <!--
-    TM & (c) 2018 Lucasfilm Entertainment Company Ltd. and Lucasfilm Ltd.
+    TM & (c) 2021 Lucasfilm Entertainment Company Ltd. and Lucasfilm Ltd.
     All rights reserved.  See LICENSE.txt for license.
 
     Declarations of standard data types and nodes included in the MaterialX specification.
@@ -246,8 +246,46 @@
     <input name="exposure" type="float" value="0.0" doc="Exposure control for the light intensity" />
     <output name="out" type="lightshader" />
   </nodedef>
-
+   
   <!--
+    Node: unlit_surface
+    Uniform emission surface shader. Variants exist for the following input types: color3, color4, vec2, vec3, vec4, and float.
+  -->
+  <nodedef name="ND_unlit_surface_color4" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a color4 input" >
+      <input name="color" type="color4" value="1, 1, 1, 1" />
+      <output name="out" type="surfaceshader" value="" />
+   </nodedef>   
+
+  <nodedef name="ND_unlit_surface_color3" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a color3 and opacity input" >
+    <input name="color" type="color3" value="1, 1, 1" />
+    <input name="opacity" type="float" value="1" />
+    <output name="out" type="surfaceshader" value="" />
+  </nodedef>
+
+  <nodedef name="ND_unlit_surface_float" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a float and opacity input" >
+    <input name="color" type="float" value="1" />
+    <input name="opacity" type="float" value="1" />
+    <output name="out" type="surfaceshader" value="" />
+  </nodedef>
+
+  <nodedef name="ND_unlit_surface_vec4" node="unlit_surface" version="1.0" isdefaultversion="true" doc="Uniform emission surface shader which accepts a vec4 input" >
+    <input name="color" type="vector4" value="1, 1, 1, 1" />
+    <output name="out" type="surfaceshader" value="" />
+  </nodedef>
+
+   <nodedef name="ND_unlit_surface_vec3" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a vec3 and opacity input" >
+      <input name="color" type="vector3" value="1, 1, 1" />
+      <input name="opacity" type="float" value="1" />
+      <output name="out" type="surfaceshader" value="" />
+   </nodedef>
+
+   <nodedef name="ND_unlit_surface_vec2" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a vec2 and opaciy input" >
+      <input name="color" type="vector2" value="1, 1" />
+      <input name="opacity" type="float" value="1" />
+      <output name="out" type="surfaceshader" value="" />
+   </nodedef>
+
+   <!--
     Node: <displacement>
     Construct a displacement shader.
   -->
diff --git a/libraries/pbrlib/pbrlib_ng.mtlx b/libraries/pbrlib/pbrlib_ng.mtlx
index fb5c2ab760..09b855f61b 100644
--- a/libraries/pbrlib/pbrlib_ng.mtlx
+++ b/libraries/pbrlib/pbrlib_ng.mtlx
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <materialx version="1.38">
   <!--
-    TM & (c) 2018 Lucasfilm Entertainment Company Ltd. and Lucasfilm Ltd.
+    TM & (c) 2021 Lucasfilm Entertainment Company Ltd. and Lucasfilm Ltd.
     All rights reserved.  See LICENSE.txt for license.
 
     Graph definitions of standard nodes included in the MaterialX specification.
@@ -18,5 +18,121 @@
     </roughness_anisotropy>
     <output name="out" type="vector2" nodename="roughness1" />
   </nodegraph>
+   
+  <!-- Uniform emission surface shader which accepts a color4 input. -->
+  <nodegraph name="NG_unlit_surface_color4"  nodedef="ND_unlit_surface_color4" >
+     <input name="color" type="color4" value="1, 1, 1, 1" />
+     <extract name="extract" type="float" nodedef="ND_extract_color4" xpos="620" ypos="205">
+        <input name="in" type="color4" interfacename="color" value="0, 0, 0, 0" />
+        <input name="index" type="integer" uniform="true" value="3" />
+     </extract>
+     <surface name="surface" type="surfaceshader" nodedef="ND_surface" xpos="925" ypos="47">
+        <input name="bsdf" type="BSDF" value="" />
+        <input name="edf" type="EDF" nodename="uniform_edf" />
+        <input name="opacity" type="float" nodename="extract" />
+     </surface>
+     <swizzle name="swizzle5" type="color3" nodedef="ND_swizzle_color4_color3" xpos="315" ypos="22">
+        <input name="in" type="color4" interfacename="color" value="0, 0, 0, 0" />
+        <input name="channels" type="string" uniform="true" value="rgb" />
+     </swizzle>
+     <uniform_edf name="uniform_edf" type="EDF" nodedef="ND_uniform_edf" xpos="620" ypos="10">
+        <input name="color" type="color3" nodename="swizzle5" />
+     </uniform_edf>
+     <output name="out" type="surfaceshader" nodename="surface" />
+  </nodegraph>
+   
+ <!-- Uniform emission surface shader which accepts a color3 and opacity input. -->
+  <nodegraph name="NG_unlit_surface_color3" nodedef="ND_unlit_surface_color3" >
+    <input name="color" type="color3" value="1, 1, 1" />
+    <input name="opacity" type="float" value="1" />
+    <surface name="surface" type="surfaceshader" >
+      <input name="bsdf" type="BSDF" value="" uivisible="false" />
+      <input name="edf" type="EDF" nodename="uniform_edf" />
+      <input name="opacity" type="float" interfacename="opacity" value="1" />
+    </surface>
+    <uniform_edf name="uniform_edf" type="EDF" >
+      <input name="color" type="color3" interfacename="color" value="1, 1, 1" />
+    </uniform_edf>
+    <output name="out" type="surfaceshader" nodename="surface" />
+  </nodegraph>
+
+  <!-- Uniform emission surface shader which accepts a float and opacity input. -->
+  <nodegraph name="NG_unlit_surface_float" nodedef="ND_unlit_surface_float"  >
+    <input name="color" type="float" value="1" />
+    <input name="opacity" type="float" value="1" />
+    <surface name="surface" type="surfaceshader" >
+      <input name="bsdf" type="BSDF" value="" uivisible="false" />
+      <input name="edf" type="EDF" nodename="uniform_edf" />
+      <input name="opacity" type="float" interfacename="opacity" value="1" />
+    </surface>
+    <uniform_edf name="uniform_edf" type="EDF" >
+      <input name="color" type="color3" nodename="convert" />
+    </uniform_edf>
+    <convert name="convert" type="color3" >
+      <input name="in" type="float" interfacename="color" value="1" />
+    </convert>
+    <output name="out" type="surfaceshader" nodename="surface" />
+  </nodegraph>
+   
+  <!-- Uniform emission surface shader which accepts a vec4 input. -->
+  <nodegraph name="NG_unlit_surface2_vec4"  nodedef="ND_unlit_surface_vec4">
+    <input name="color" type="vector4" value="1, 1, 1, 1" />
+    <extract name="extract1" type="float" nodedef="ND_extract_vector4" xpos="620" ypos="203.811">
+      <input name="in" type="vector4" interfacename="color" value="0, 0, 0, 0" />
+      <input name="index" type="integer" uniform="true" value="3" />
+    </extract>
+    <surface name="surface" type="surfaceshader" nodedef="ND_surface" xpos="925" ypos="48">
+      <input name="bsdf" type="BSDF" value="" />
+      <input name="edf" type="EDF" nodename="uniform_edf1" />
+      <input name="opacity" type="float" nodename="extract1" />
+    </surface>
+    <swizzle name="swizzle4" type="color3" nodedef="ND_swizzle_vector4_color3" xpos="315" ypos="22">
+      <input name="in" type="vector4" interfacename="color" value="0, 0, 0, 0" />
+      <input name="channels" type="string" uniform="true" value="xyz" />
+    </swizzle>
+    <uniform_edf name="uniform_edf1" type="EDF" nodedef="ND_uniform_edf" xpos="620" ypos="10">
+      <input name="color" type="color3" nodename="swizzle4" />
+    </uniform_edf>
+    <output name="out" type="surfaceshader" nodename="surface" />
+  </nodegraph>   
+
+  <!-- Uniform emission surface shader which accepts a vec3 and opacity input. -->
+  <nodegraph name="NG_unlit_surface_vec3" xpos="345.014"  nodedef="ND_unlit_surface_vec3"  >
+    <input name="color" type="vector3" value="1, 1, 1" />
+    <input name="opacity" type="float" value="1" />
+    <surface name="surface" type="surfaceshader" >
+      <input name="bsdf" type="BSDF" value="" uivisible="false" />
+      <input name="edf" type="EDF" nodename="uniform_edf" />
+      <input name="opacity" type="float" interfacename="opacity" value="1" />
+    </surface>
+    <uniform_edf name="uniform_edf" type="EDF" >
+      <input name="color" type="color3" nodename="convert" />
+    </uniform_edf>
+    <convert name="convert" type="color3" >
+      <input name="in" type="vector3" interfacename="color" value="1, 1, 1" />
+    </convert>
+    <output name="out" type="surfaceshader" nodename="surface" />
+  </nodegraph>
+  
+  <!-- Uniform emission surface shader which accepts a vec2 and opaciy input. -->
+  <nodegraph name="NG_unlit_surface_vec2" nodedef="ND_unlit_surface_vec2"  >
+    <input name="color" type="vector2" value="1, 1" />
+    <input name="opacity" type="float" value="1" />
+    <surface name="surface" type="surfaceshader" >
+      <input name="bsdf" type="BSDF" value="" uivisible="false" />
+      <input name="edf" type="EDF" nodename="uniform_edf" />
+      <input name="opacity" type="float" interfacename="opacity" value="1" />
+    </surface>
+    <uniform_edf name="uniform_edf" type="EDF" >
+      <input name="color" type="color3" nodename="convert1" />
+    </uniform_edf>
+    <convert name="convert" type="vector3" >
+      <input name="in" type="vector2" interfacename="color" value="1, 1" />
+    </convert>
+    <convert name="convert1" type="color3" >
+      <input name="in" type="vector3" nodename="convert" />
+    </convert>
+    <output name="out" type="surfaceshader" nodename="surface" />
+  </nodegraph>   
 
 </materialx>
diff --git a/libraries/pbrlib/unlit_surface.mtlx b/libraries/pbrlib/unlit_surface.mtlx
deleted file mode 100644
index b66ae56910..0000000000
--- a/libraries/pbrlib/unlit_surface.mtlx
+++ /dev/null
@@ -1,147 +0,0 @@
-<?xml version="1.0"?>
-<materialx version="1.38">
-
-  <!-- Uniform emission surface shader which accepts a color4 input. -->
-  <nodedef name="ND_unlit_surface_color4" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a color4 input" >
-    <input name="color" type="color4" value="1, 1, 1, 1" />
-    <output name="out" type="surfaceshader" value="" />
-  </nodedef>
-  <nodegraph name="NG_unlit_surface_color4"  nodedef="ND_unlit_surface_color4" >
-     <input name="color" type="color4" value="1, 1, 1, 1" />
-     <extract name="extract" type="float" nodedef="ND_extract_color4" xpos="620" ypos="205">
-        <input name="in" type="color4" interfacename="color" value="0, 0, 0, 0" />
-        <input name="index" type="integer" uniform="true" value="3" />
-     </extract>
-     <surface name="surface" type="surfaceshader" nodedef="ND_surface" xpos="925" ypos="47">
-        <input name="bsdf" type="BSDF" value="" />
-        <input name="edf" type="EDF" nodename="uniform_edf" />
-        <input name="opacity" type="float" nodename="extract" />
-     </surface>
-     <swizzle name="swizzle5" type="color3" nodedef="ND_swizzle_color4_color3" xpos="315" ypos="22">
-        <input name="in" type="color4" interfacename="color" value="0, 0, 0, 0" />
-        <input name="channels" type="string" uniform="true" value="rgb" />
-     </swizzle>
-     <uniform_edf name="uniform_edf" type="EDF" nodedef="ND_uniform_edf" xpos="620" ypos="10">
-        <input name="color" type="color3" nodename="swizzle5" />
-     </uniform_edf>
-     <output name="out" type="surfaceshader" nodename="surface" />
-  </nodegraph>
-   
- <!-- Uniform emission surface shader which accepts a color3 and opacity input. -->
- <nodedef name="ND_unlit_surface_color3" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a color3 and opacity input" >
-    <input name="color" type="color3" value="1, 1, 1" />
-    <input name="opacity" type="float" value="1" />
-    <output name="out" type="surfaceshader" value="" />
-  </nodedef>
-  <nodegraph name="NG_unlit_surface_color3" nodedef="ND_unlit_surface_color3" >
-    <input name="color" type="color3" value="1, 1, 1" />
-    <input name="opacity" type="float" value="1" />
-    <surface name="surface" type="surfaceshader" >
-      <input name="bsdf" type="BSDF" value="" uivisible="false" />
-      <input name="edf" type="EDF" nodename="uniform_edf" />
-      <input name="opacity" type="float" interfacename="opacity" value="1" />
-    </surface>
-    <uniform_edf name="uniform_edf" type="EDF" >
-      <input name="color" type="color3" interfacename="color" value="1, 1, 1" />
-    </uniform_edf>
-    <output name="out" type="surfaceshader" nodename="surface" />
-  </nodegraph>
-
-  <!-- Uniform emission surface shader which accepts a float and opacity input. -->
-  <nodedef name="ND_unlit_surface_float" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a float and opacity input" >
-    <input name="color" type="float" value="1" />
-    <input name="opacity" type="float" value="1" />
-    <output name="out" type="surfaceshader" value="" />
-  </nodedef>
-  <nodegraph name="NG_unlit_surface_float" nodedef="ND_unlit_surface_float"  >
-    <input name="color" type="float" value="1" />
-    <input name="opacity" type="float" value="1" />
-    <surface name="surface" type="surfaceshader" >
-      <input name="bsdf" type="BSDF" value="" uivisible="false" />
-      <input name="edf" type="EDF" nodename="uniform_edf" />
-      <input name="opacity" type="float" interfacename="opacity" value="1" />
-    </surface>
-    <uniform_edf name="uniform_edf" type="EDF" >
-      <input name="color" type="color3" nodename="convert" />
-    </uniform_edf>
-    <convert name="convert" type="color3" >
-      <input name="in" type="float" interfacename="color" value="1" />
-    </convert>
-    <output name="out" type="surfaceshader" nodename="surface" />
-  </nodegraph>
-   
-  <!-- Uniform emission surface shader which accepts a vec4 input. -->
-  <nodedef name="ND_unlit_surface_vec4" node="unlit_surface" version="1.0" isdefaultversion="true" doc="Uniform emission surface shader which accepts a vec4 input" >
-    <input name="color" type="vector4" value="1, 1, 1, 1" />
-    <output name="out" type="surfaceshader" value="" />
-  </nodedef>
-  <nodegraph name="NG_unlit_surface2_vec4"  nodedef="ND_unlit_surface_vec4">
-    <input name="color" type="vector4" value="1, 1, 1, 1" />
-    <extract name="extract1" type="float" nodedef="ND_extract_vector4" xpos="620" ypos="203.811">
-      <input name="in" type="vector4" interfacename="color" value="0, 0, 0, 0" />
-      <input name="index" type="integer" uniform="true" value="3" />
-    </extract>
-    <surface name="surface" type="surfaceshader" nodedef="ND_surface" xpos="925" ypos="48">
-      <input name="bsdf" type="BSDF" value="" />
-      <input name="edf" type="EDF" nodename="uniform_edf1" />
-      <input name="opacity" type="float" nodename="extract1" />
-    </surface>
-    <swizzle name="swizzle4" type="color3" nodedef="ND_swizzle_vector4_color3" xpos="315" ypos="22">
-      <input name="in" type="vector4" interfacename="color" value="0, 0, 0, 0" />
-      <input name="channels" type="string" uniform="true" value="xyz" />
-    </swizzle>
-    <uniform_edf name="uniform_edf1" type="EDF" nodedef="ND_uniform_edf" xpos="620" ypos="10">
-      <input name="color" type="color3" nodename="swizzle4" />
-    </uniform_edf>
-    <output name="out" type="surfaceshader" nodename="surface" />
-  </nodegraph>   
-
-  <!-- Uniform emission surface shader which accepts a vec3 and opacity input. -->
-  <nodedef name="ND_unlit_surface_vec3" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a vec3 and opacity input" >
-    <input name="color" type="vector3" value="1, 1, 1" />
-    <input name="opacity" type="float" value="1" />
-    <output name="out" type="surfaceshader" value="" />
-  </nodedef>
-  <nodegraph name="NG_unlit_surface_vec3" xpos="345.014"  nodedef="ND_unlit_surface_vec3"  >
-    <input name="color" type="vector3" value="1, 1, 1" />
-    <input name="opacity" type="float" value="1" />
-    <surface name="surface" type="surfaceshader" >
-      <input name="bsdf" type="BSDF" value="" uivisible="false" />
-      <input name="edf" type="EDF" nodename="uniform_edf" />
-      <input name="opacity" type="float" interfacename="opacity" value="1" />
-    </surface>
-    <uniform_edf name="uniform_edf" type="EDF" >
-      <input name="color" type="color3" nodename="convert" />
-    </uniform_edf>
-    <convert name="convert" type="color3" >
-      <input name="in" type="vector3" interfacename="color" value="1, 1, 1" />
-    </convert>
-    <output name="out" type="surfaceshader" nodename="surface" />
-  </nodegraph>
-  
-  <!-- Uniform emission surface shader which accepts a vec2 and opaciy input. -->
-  <nodedef name="ND_unlit_surface_vec2" node="unlit_surface" version="1.0" isdefaultversion="true" nodegroup="pbr" doc="Uniform emission surface shader which accepts a vec2 and opaciy input" >
-    <input name="color" type="vector2" value="1, 1" />
-    <input name="opacity" type="float" value="1" />
-    <output name="out" type="surfaceshader" value="" />
-  </nodedef>
-  <nodegraph name="NG_unlit_surface_vec2" nodedef="ND_unlit_surface_vec2"  >
-    <input name="color" type="vector2" value="1, 1" />
-    <input name="opacity" type="float" value="1" />
-    <surface name="surface" type="surfaceshader" >
-      <input name="bsdf" type="BSDF" value="" uivisible="false" />
-      <input name="edf" type="EDF" nodename="uniform_edf" />
-      <input name="opacity" type="float" interfacename="opacity" value="1" />
-    </surface>
-    <uniform_edf name="uniform_edf" type="EDF" >
-      <input name="color" type="color3" nodename="convert1" />
-    </uniform_edf>
-    <convert name="convert" type="vector3" >
-      <input name="in" type="vector2" interfacename="color" value="1, 1" />
-    </convert>
-    <convert name="convert1" type="color3" >
-      <input name="in" type="vector3" nodename="convert" />
-    </convert>
-    <output name="out" type="surfaceshader" nodename="surface" />
-  </nodegraph>
-</materialx>