P

paintEffectsDisplay
pairBlend
palettePort
panel
paneLayout
panelConfiguration
panelHistory
paramDimContext
paramDimension
paramLocator
parent
parentConstraint
particle
particleExists
particleFill
particleInstancer
particleRenderInfo
partition
pasteKey
pathAnimation
pause
pclose
percent
performanceOptions
pfxstrokes
pickWalk
picture
pixelMove
planarSrf
plane
play
playbackOptions
playblast
plugAttr 
pluginInfo
pluginResourceUtil 
plugMultiAttrs 
plugNode 
plugNodeStripped 
pointConstraint
pointCurveConstraint
pointLight
pointMatrixMult 
pointOnCurve
pointOnSurface
pointPosition
poleVectorConstraint
polyAppend
polyAppendFacetCtx
polyAppendVertex
polyAutoProjection
polyAverageNormal
polyAverageVertex
polyBevel
polyBlendColor
polyBlindData
polyBoolOp
polyBridgeEdge
polyCacheMonitor
polyCheck
polyChipOff
polyClipboard
polyCloseBorder
polyCollapseEdge
polyCollapseFacet
polyColorBlindData
polyColorDel
polyColorMod
polyColorPerVertex
polyColorSet
polyCompare
polyCone
polyCopyUV
polyCrease
polyCreaseCtx
polyCreateFacet
polyCreateFacetCtx
polyCube
polyCut
polyCutCtx
polyCylinder
polyCylindricalProjection
polyDelEdge
polyDelFacet
polyDelVertex
polyDuplicateAndConnect
polyDuplicateEdge
polyEditUV
polyEditUVShell
polyEvaluate
polyExtrudeEdge
polyExtrudeFacet
polyExtrudeVertex
polyFlipEdge
polyFlipUV
polyForceUV
polyGeoSampler
polyHelix
polyInfo
polyInstallAction
polyLayoutUV
polyListComponentConversion
polyMapCut
polyMapDel
polyMapSew
polyMapSewMove
polyMergeEdge
polyMergeEdgeCtx
polyMergeFacet
polyMergeFacetCtx
polyMergeUV
polyMergeVertex
polyMirrorFace
polyMoveEdge
polyMoveFacet
polyMoveFacetUV
polyMoveUV
polyMoveVertex
polyMultiLayoutUV
polyNormal
polyNormalizeUV
polyNormalPerVertex
polyOptions
polyOptUvs
polyOutput
polyPipe
polyPlanarProjection
polyPlane
polyPlatonicSolid
polyPoke
polyPrimitive
polyPrism
polyProjection
polyPyramid
polyQuad
polyQueryBlindData
polyReduce
polySelect
polySelectConstraint
polySelectConstraintMonitor
polySelectCtx
polySelectEditCtx
polySeparate
polySetToFaceNormal
polySewEdge
polyShortestPathCtx
polySlideEdge
polySmooth
polySoftEdge
polySphere
polySphericalProjection
polySplit
polySplitCtx
polySplitEdge
polySplitRing
polySplitVertex
polyStraightenUVBorder
polySubdivideEdge
polySubdivideFacet
polyTorus
polyToSubdiv
polyTransfer
polyTriangulate
polyUnite
polyUVSet
polyWedgeFace
popen
popupMenu
pose
pow
preloadRefEd
print
progressBar
progressWindow
projectCurve
projectionContext
projectionManip
projectTangent
projFileViewer
promptDialog
propModCtx
propMove
psdChannelOutliner
psdEditTextureFile
psdExport
psdTextureFile
publishAnchorNodes 
publishContainerConnections 
putenv
pwd
python

indicates a MEL script