Here is a list of all namespaces with brief descriptions:

[detail level 123]

NATS
NCatAPI
NCommonRendererUI	This namespace aggregates various UI functionality to be shared by renderers
NGFX_MESH
NIKSys
NImportExportInterface
NLightingModel
NManagedServices
NMax
NRenderingAPI
NMaxGraphics
NBackfaceWireframe
NMAXScript
NMaxSDK
NAssetManagement
NChannelData	These are classes and enums to support the Data Channel Modifier
NColorManagement
NCUI
NCustomFileStreamAPI	This API is used to support OLE structured storage streams containing user specified string data in 3ds Max scene files or other OLE Structured Storage based files
NDebuggingTools
NGeomBind	These classes let you define skin weighting using a voxel or height map based algorithm
NGraphics
NHelperFunctionsBaseRaster
NMaterialConversionHelper	MaterialConversionHelper is a class to convert from a 3ds Max material (Mtl class) into a Viewport material (BaseMaterialHandle class) This viewport material can be assigned with :
NUtilities
NViewportInstancing	This API is about having a single INode in the scene, but having many geometries being instantiated at the GPU level in the viewport when the INode is drawn, e.g : a particles system
NViewportVolumeDisplay	Volume Display functions for 3ds Max's viewport This is a set of functions for an Object plug-in to support a volume display in the viewport Link with MaxGraphics.lib when using this header
NNotificationAPI
NNotificationAPIUtils	This namespace exposes 4 private internal calls to the 3dsmax application
NOSL
NParticleFlow
NPerformanceTools
NPointCloud
NPopulate
NRenderingAPI
NTranslationHelpers
NRenderTimeInstancing	This API is meant to be implemented by plugins and used by renderers to instantiate objects at render-time
NSkinEngine
NThreadingDebuggingTools	The functions in this namespace are provided to assist in debugging operations performed on a worker thread
NTranslationSupport	MAXScript scripts are typically written in English, but when MAXScript accesses names from TrackView nodes only localized names are available
NUtil
NDebugHelpers
NTextFile
NNodeEventNamespace
NPF
NQtHelpers
NSceneEventNamespace
NSlate
Nstd
NToolClips
NUI	Namespace UI (Userinterface) Containing the namespace, EMouseCursors containing the function to load the cursors
NMouseCursors
NUtilityInterface