diff --git a/3_SceneGraph/osg2vsg.md b/3_SceneGraph/osg2vsg.md
index 1379838..abdf604 100644
--- a/3_SceneGraph/osg2vsg.md
+++ b/3_SceneGraph/osg2vsg.md
@@ -40,7 +40,7 @@ permalink: /scenegraph/osg2vsg
 | [`osg::PagedLOD`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/PagedLOD) | [`vsg::PagedLOD`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/nodes/PagedLOD.h)  |  |
 | [`osg::Transform`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/Transform) | [`vsg::Transform`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/nodes/Transform,h)  | Both base classes for providing model transforms |
 | [`osg::MatrixTransform`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/MatrixTransform) | [`vsg::MatrixTransform`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/nodes/MatrixTransform,h)  |  |
-| [`osg::MatrixTransform`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/MatrixTransform) | [`vsg::AbsoluteTransform`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/nodes/AbsoluteTransform,h)  |  osg::MatrixTransform::setReferenceFrame(ABSOLUTE_RF) equivalent to vsg::AbsoluteTransform |
+| [`osg::MatrixTransform`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/MatrixTransform) | [`vsg::AbsoluteTransform`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/nodes/AbsoluteTransform,h)  |  osg::MatrixTransform::[setReferenceFrame(ABSOLUTE_RF)](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/Transform#97) equivalent to vsg::AbsoluteTransform |
 | [`osg::PositionAttitudeTransform`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/PositionAttitudeTransform) |  | No VSG equivalent |
 | [`osg::AutoTransform`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/AutoTransform) |  | No VSG equivalent |
 | [`osg::Billboard`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osg/Billboard) |  | No VSG equivalent - use instanced geometry and vertex shader. |
@@ -87,7 +87,28 @@ permalink: /scenegraph/osg2vsg
 
 | OSG | VSG | Notes |
 | --- | --- | --- |
+| [`osgViewer::View`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osgViewer/View.h) | [`vsg::View`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/app/View.h)  |  |
+| [`osgViewer::Viewer`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osgViewer/Viewer.h) | [`vsg::Viewer`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/app/Viewer.h)  |  |
+| [`osgViewer::CompositeViewer`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osgViewer/CompositeViewer.h) | [`vsg::Viewer`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/app/Viewer.h)  |  |
 | [`osgViewer::`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/osgViewer/) | [`vsg::`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/app/)  |  |
 
+## Threading
+
+| OSG | VSG | Notes |
+| --- | --- | --- |
+| (`OpenThreads::Thread`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Thread) | std::thread | |
+| (`OpenThreads::Mutex`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Mutex) | std::mutex| |
+| (`OpenThreads::ScopedLock`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Block.h) | std::lock | |
+| (`OpenThreads::Atomoic`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Atomic) | std::atomic | |
+| (`OpenThreads::Condition`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Condition) | std::condition_variable | |
+| (`OpenThreads::Barrier`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Barrier) | [`vsg::Barrier`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/threading/Barrier.h) | |
+| (`OpenThreads::Block`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Block) | [`vsg::Latch`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/threading/Latch.h) | |
+VulkanSceneGraph/blob/master/include/vsg/threading/Affinity.h) | |
+|  [`osg::OperationThread`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/osg/OperationThread) | [`vsg::OperationThread`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/threading/OperationThread.h) |  |
+|  [`osg::OperationThread`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/osg/OperationThread) | [`vsg::OperationQueue`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/threading/OperationQueue.h) |  |
+|  [`osg::Operation`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/osg/OperationThread) | [`vsg::Operation`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/threading/OperationQueue.h) |  |
+|  | [`vsg::ActivityStatus`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/threading/ActivityStatus.h) | No OSG equvalent, used to cooperatively release barriers & blocks. |
+| | [`vsg::FrameBlock`](https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/threading/FrameBlock.h) | No direct OSG equvalent, loosely OpenThreds::Block. |
+| (`OpenThreads::Affinity`](https://github.com/openscenegraph/OpenSceneGraph/blob/master/include/OpenThraeds/Affinity) | [`vsg::Affinity`](https://github.com/vsg-dev/
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