Here is a list of all namespaces with brief descriptions:

[detail level 12345]

_Detail
Alembic	Alembic namespace ..
Abc
ALEMBIC_VERSION_NS
AbcCollection
ALEMBIC_VERSION_NS
AbcCoreAbstract
ALEMBIC_VERSION_NS
IllustrationOnly
AbcCoreFactory
ALEMBIC_VERSION_NS
AbcCoreHDF5
ALEMBIC_VERSION_NS
AbcCoreLayer
ALEMBIC_VERSION_NS
AbcCoreOgawa
ALEMBIC_VERSION_NS
AbcGeom
ALEMBIC_VERSION_NS
AbcMaterial
ALEMBIC_VERSION_NS
Util
ALEMBIC_VERSION_NS
align
ankerl
nanobench
apex
detail
APEX_Names
bjhash
BRAY
CE_OSDPatchEval
CE_Snippet
cl	The OpenCL C++ bindings are defined within this namespace
detail
CubeMap
cv
detail
dragonbox
detail_exported
digits
draco
dragonbox
Eigen
enums
exec_registration
EXPR
farmhash
farmhashcc
farmhashmk
farmhashna
farmhashnt
farmhashsa
farmhashsu
farmhashte
farmhashuo
farmhashxo
inlined
fasthash
FBX_Names
Filesystem	Platform-independent utilities for manipulating file names, files, directories, and other file system miscellany
fmt	Custom fmtlib formatters for our SIMD types
FS
FS_StaleUSDFiles
GA_FileFormatH9
GA_HandleDetail
GA_Homogenize	Homogenize/dehomogenize that only operate on UT_Vector4
GA_Names
GA_PageArrayIO
GA_PrimCompat
GA_Private
GABC_NAMESPACE
GABC_GTUtil
GD_PrimTypeCompat
GEO
geo_hedge
GEO_ImplicitSurfaceOps
GEO_PrimTypeCompat
GEO_StandardAttribs	Utilities for the standard attributes defined in GA_Names
GLTF_CgltfUtils
GLTF_Names
GLTF_NAMESPACE
GQ_PolyDelaunayImpl
GQ_StraightSkeletonImpl
GR_ShapeFactory
GR_Utils	Utility GR methods common to all renderers
GT_DeformUtils
GT_GUHelpers
GT_Names
GT_PointSplat
GU
GU_AgentBlendShapeUtils
GU_Blend
GU_Classify
GU_CleanTools
GU_Copy
NeededTransforms
GU_Cosserat
GU_CurveFrame
GU_Decomposition
GU_EdgeSplitUtils
GU_ExtractTransform
GU_Flatten2
GU_Hierarchy
GU_LocalFrame
GU_LocalTransform
GU_MotionClipNames
GU_OSDPatchMap
GU_PackedFactoryPrivate
GU_PointDeform
GU_PolyFill
GU_ShrinkTools
GU_Snap
GU_SurfaceDeform
GU_VDBPointToolsInternal
GU_Xform
GusdUSD_StdTraverse
GusdUSD_ThreadedTraverse
GusdUSD_Utils
hboost
program_options
HdFlatteningSceneIndex_Impl
HDK_Sample	This namespace is used to hold all HDK example source code
GU_Copy
NeededTransforms
GU_CurveFrame
UT
HdMakeDataSourceContainingFlattenedDataSourceProvider
HdsiDebuggingSceneIndex_Impl
HdsiLegacyDisplayStyleSceneIndex_Impl
HdsiLightLinkingSceneIndex_Impl
HdsiSceneMaterialPruningSceneIndex_Impl
HdSkinningSettings
HdUtils
HdxFreeCameraPrimDataSource_Impl
HOIIO_v2_5
HUSD_RenderTokens
HW	HW specific identifiers
IEX_INTERNAL_NAMESPACE
IEX_NAMESPACE
ILMTHREAD_INTERNAL_NAMESPACE
ILMTHREAD_NAMESPACE
ImageBufAlgo
Imath
IMG_GammaTable
internal
GLApi
LatLongMap
MATERIALX_NAMESPACE_BEGIN
MaterialX_v1_39_5
MDL
murmur
nanovdb
build
crc32
io
Internal	Internal functions for compressed read/write of a NanoVDB GridHandle into a stream
NET
NET_ConvertToType
OCIO_NAMESPACE
ColorSpaceHelpers
ConfigMergingHelpers
DisplayViewHelpers
DynamicPropertyValue
ONNX_NAMESPACE
onnxruntime
common
concurrency
contrib
cuda
js
rocm
snpe
data_types_internal
detail
details
fbs
logging
lora
ml
optimizer_utils
profiling
synchronize
utils
data_types_internal
mltype_dispatcher_internal
onnxruntime_float16
detail
OP_Utils
OPENEXR_IMF_INTERNAL_NAMESPACE
OPENEXR_IMF_NAMESPACE
OpenSubdiv
OPENSUBDIV_VERSION
Far
openvdb
OPENVDB_VERSION_NAME
compression
internal
io
logging
math
internal
mat3_internal
pcg
internal
points
attribute_traits
future	A container for ABI=5 to help ease introduction of upcoming features
index
internal
point_attribute_internal
point_move_internal
point_rasterize_internal
transfer_internal
string
thread
tools
composite
ds
gridop
local_util
lstrack
lvlset
morphology
poisson
Scheme
valxform
tree
iter
leafmgr
types_internal
util
Ort	All C++ Onnxruntime APIs are defined inside this namespace
Custom
detail
attr_utils
binding_utils
Experimental
OSL
OSLNetwork
PDGN
PI_PythonHandle
PI_PythonResource
PI_PythonState
Plugin
pss
internal
pugi
pvt
PXL_OCIO	Abstract interface to OpenColorIO
PXR_BOOST_NAMESPACE
python
detail
pxr_CLI
CLI
detail
enums
FailureMessage
pxr_half
PXR_INTERNAL_NS
PXR_NAMESPACE_OPEN_SCOPE
PXR_NS
pxr_tsl
detail_robin_hash
rh
detail
PyImath
detail
RE_Utils
RgbaYca
RV_Utils
safe_duration_cast
Sdf_PySpecDetail
Sdf_VariableExpressionImpl
SdfPathPatternActions
SdfPathPatternParser
SdfPredicateExpressionParser
SdfVariableExpressionASTNodes
SdrShaderNodeQueryUtils
ShaderMetadataHelpers
sign
SIM
FieldUtils
SIM_ConstraintNetwork
Names	Standard attribute names
SIM_Detail
simd
SOP_AddEnums
SOP_AgentUnpackEnums
SOP_AttribCombineEnums
SOP_AttribCopyEnums
SOP_AttribCreate_2_0Enums
SOP_AttribFillEnums
SOP_AttribFromParmEnums
SOP_AttribFromVolumeEnums
SOP_AttribInterpolateEnums
SOP_AttribMirrorEnums
SOP_AttribPromoteEnums
SOP_AttribSortEnums
SOP_AttribSwapEnums
SOP_AttribTransferEnums
SOP_BasisEnums
SOP_BlastEnums
SOP_BlendShapes_2_0Enums
SOP_BoneCaptureBiharmonicEnums
SOP_BoneCaptureLinesEnums
SOP_BoneDeformEnums
SOP_BooleanEnums
SOP_BoundEnums
SOP_BoxEnums
SOP_CacheIfEnums
SOP_CameraEditEnums
SOP_CameraEnums
SOP_CameraToPointsEnums
SOP_CapEnums
SOP_CaptureAttribPackEnums
SOP_CaptureAttribUnpackEnums
SOP_CircleEnums
SOP_CircleFromEdgesEnums
SOP_Clip_2_0Enums
SOP_ClipEnums
SOP_CollisionDetectCLEnums
SOP_ConnectivityEnums
SOP_ControlEnums
SOP_ConvertEnums
SOP_ConvexDecompositionEnums
SOP_CopyToPoints_2_0Enums
SOP_CopyToPointsEnums
SOP_CopyTransformEnums
SOP_CreaseEnums
SOP_CrowdMotionPathAvoidCoreEnums
SOP_Curve_3_0Enums
SOP_CurveEnums
SOP_CurveFrameEnums
SOP_CurveNetworkEnums
SOP_CurvesectEnums
SOP_DeleteEnums
SOP_Dissolve_2_0Enums
SOP_EdgeEqualizeEnums
SOP_EdgeStraightenEnums
SOP_EdgeTransportEnums
SOP_EndsEnums
SOP_EnumerateEnums
SOP_ErrorNodeEnums
SOP_ExtractCentroidEnums
SOP_ExtractTransformEnums
SOP_FacetEnums
SOP_FeatherAttribInterpolateEnums
SOP_FileEnums
SOP_FitEnums
SOP_Fuse_2_0Enums
SOP_FuseEnums
SOP_GridEnums
SOP_GroupCombineEnums
SOP_GroupCreateEnums
SOP_GroupDeleteEnums
SOP_GroupExpandEnums
SOP_GroupFindPathEnums
SOP_GroupInvertEnums
SOP_GroupPromoteEnums
SOP_GroupRangeEnums
SOP_GroupRenameEnums
SOP_GroupsFromNameEnums
SOP_GuideDeformCoreEnums
SOP_GuideGroomCoreEnums
SOP_GuideMaskEnums
SOP_GuideProcessCoreEnums
SOP_HairClumpEnums
SOP_HairGenCoreEnums
SOP_InflateEnums
SOP_InvokeEnums
SOP_InvokeGraphEnums
SOP_JoinEnums
SOP_KnifeEnums
SOP_LinearSolverEnums
SOP_LineEnums
SOP_MaterialEnums
SOP_Measure_2_0Enums
SOP_MeasureEnums
SOP_MergePackedEnums
SOP_MirrorEnums
SOP_MLExampleDecomposeCoreEnums
SOP_MLExampleDeserializePackedEnums
SOP_MLExampleSerializePackedEnums
SOP_MLPoseDeserializeCoreEnums
SOP_MLPoseFromSkinCoreEnums
SOP_MLPoseSerializeCoreEnums
SOP_MLRegressionInferenceCoreEnums
SOP_MLRegressionKernelCoreEnums
SOP_MLRegressionLinearCoreEnums
SOP_MLRegressionProximityCoreEnums
SOP_NameEnums
SOP_NormalEnums
SOP_ONNXEnums
SOP_OpenCLEnums
SOP_PackedEditEnums
SOP_PackFolderEnums
SOP_PackInjectEnums
SOP_PackPointsEnums
SOP_PCAEnums
SOP_PeakEnums
SOP_PointCaptureCoreEnums
SOP_PointCloudNormalEnums
SOP_PointCloudReduceEnums
SOP_PointCloudSurfaceEnums
SOP_PolyBevel_3_0Enums
SOP_PolyCutEnums
SOP_PolyDoctorEnums
SOP_PolyExpand2DEnums
SOP_PolyExtrude_2_0Enums
SOP_PolyFillEnums
SOP_PolyFrameEnums
SOP_PolyPatchEnums
SOP_PolyReduce_2_0Enums
SOP_PolySplit2Enums
SOP_PolyWireEnums
SOP_PrimitiveEnums
SOP_ProximityCaptureEnums
SOP_QuadRemeshEnums
SOP_RawImportEnums
SOP_RayEnums
SOP_RefineEnums
SOP_Remesh_2_0Enums
SOP_ResampleEnums
SOP_RestEnums
SOP_ReverseEnums
SOP_RevolveEnums
SOP_RewireEnums
SOP_SBlend_2_0Enums
SOP_Scatter_2_0Enums
SOP_ShapeDiffEnums
SOP_SimplexRefineEnums
SOP_Smooth_2_0Enums
SOP_SoftPeakEnums
SOP_SoftTransformEnums
SOP_SortEnums
SOP_SphereEnums
SOP_SplitPointsEnums
SOP_SurfaceDeformCoreEnums
SOP_Sweep_2_0Enums
SOP_SwitchIfEnums
SOP_TangentFieldDeformEnums
SOP_TangentFieldEnums
SOP_TetCraftEnums
SOP_TetLayerEnums
SOP_Tetrahedralize_2_0Enums
SOP_TextureFeatureEnums
SOP_TextureOpticalFlowEnums
SOP_TopoTransferEnums
SOP_TorusEnums
SOP_TraceEnums
SOP_TransformAxisEnums
SOP_TransformByAttribEnums
SOP_TransformEnums
SOP_Triangulate2D_2_0Enums
SOP_Triangulate2D_3_0Enums
SOP_TubeEnums
SOP_UnsubdivideEnums
SOP_UVAutoseamEnums
SOP_UVFlatten_2_0Enums
SOP_UVFlatten_3_0Enums
sop_uvflatten_private
SOP_UVFlattenFromPointsEnums
SOP_UVFuseEnums
SOP_UVLayout_2_0Enums
SOP_UVLayout_3_0Enums
sop_uvlayout_private
sop_uvpelt2_private
SOP_UVProjectEnums
SOP_UVRelaxEnums
SOP_UVTransform_2_0Enums
SOP_UVUnwrapEnums
SOP_VisibilityEnums
SOP_VolumeAnalysisEnums
SOP_VolumeBinEnums
SOP_VolumeBlurEnums
SOP_VolumeBoundEnums
SOP_VolumeBreakEnums
SOP_VolumeCombineEnums
SOP_VolumeCompressEnums
SOP_VolumeConvolve3Enums
SOP_VolumeFeatherEnums
SOP_VolumeFFTEnums
SOP_VolumeFromAttribEnums
SOP_VolumeMergeEnums
SOP_VolumeMixEnums
SOP_VolumeNormalizeEnums
SOP_VolumeRasterizeLatticeEnums
SOP_VolumeRasterizeParticlesEnums
SOP_VolumeReduceEnums
SOP_VolumeResampleEnums
SOP_VolumeResizeEnums
SOP_VolumeSliceEnums
SOP_VolumeTrailEnums
SOP_VolumeVisualizationEnums
SOP_VolumeVopEnums
SOP_VoronoiSplit_2_0Enums
SOP_VoronoiSplitEnums
SOP_WalkOnSurfaceEnums
SOP_WatershedEnums
SOP_WeightArrayBiharmonicEnums
SOP_WindingNumberEnums
SOP_WireEnums
Stage
std	Std::hash specialization for UT_IntrusivePtr<T>
Strutil	String-related utilities
fmt
old
pvt
sync
SYS_AtomicImpl
Sysutil	Platform-independent utilities for various OS, hardware, and system resource functionality
TCB_SPAN_NAMESPACE_NAME
detail
Tex
Tf_MakePyConstructor
Tf_PyClassMethod
Tf_PyDefHelpers
Tf_PySingleton
TfPyContainerConversions
TfPyOptional
TfType_WrapHelpers
TIL_Stitch	Combine a number of separate tiles into a single image
tinybvh
tinyobj
Type
UN_DataBufferUtils	Utility functions that operate on data buffers
UN_GraphUtils
UN_NodeUtils
UN_ParmUtils
UN_PortUtils
UN_StickyNoteUtils
UN_Utils	A namespace for UN library utility functions
UN_WireUtils
UNI_GraphUtils
UsdImaging_PrototypeSceneIndexUtils
UsdImagingDataSourceMapped_Impl
UsdImagingExtentResolvingSceneIndex_Impl
UsdImagingGLEngine_Impl
UsdImagingPiPrototypePropagatingSceneIndex_Impl
UsdImagingRootOverridesSceneIndex_Impl
UsdImagingSelectionSceneIndex_Impl
UT
detail
FA
Format
Impl
Literal
UT_AbortableLockImpl
UT_Compare
UT_CovarianceMatrix
UT_Detail
UT_Gallery
UT_GeometryPredicate
ut_internal
UT_MemLeakDetectorImpl
UT_NonCopyableNS
UT_Package
utils
UT_ParallelPipeline
UT_Permute
UT_Relacy
UT_ScopeGuard
UT_SimplexNoise
UT_SubSystemImpl
UT_SymbolTableDetail
UT_ThreadSpecificValueDetail
UT_TimeGateImpl
UT_TupleUtilImpl
UT_VDBUtils
util
VdfTestUtils
VEX
Literal
VEX_DataObjID
VEX_Geo
VIS_Flags
Vt_HashDetail
Vt_KnownValueTypeDetail
Vt_ValueVisitDetail
Vt_WrapArray
VULKAN_HPP_NAMESPACE
VULKAN_HPP_RAII_NAMESPACE
Xdr
XUSD_HydraUtils
xxhash