There is Synchronized Multimedia Integration Language 1.0. It has no namespace. Probably because it was from 1998 and Namespaces in XML became a recommendation in 1999. According to some text in a SMIL 2.0 module the namespace might have become: http://www.w3.org/TR/REC-smil
. This is not entirely clear given that normally the pointer to the specification is very different from the pointer to the namespace and it violates the namespace policy from the W3C. Of course, SMIL 1.0 predates that policy so that might be the explanation.
After SMIL 1.0 came SMIL 2.0 not to be confused with the document that is currently hosted at http://www.w3.org/TR/SMIL/
or http://www.w3.org/TR/SMIL2/
. It is located at a place quite hard to find. Now when you read 2.3.3 Identifiers for SMIL 2.0 Modules and Features you might think you are looking at feature identifiers but you are actually looking at a long list of namespaces. You can find partial proof for that in bullet point nine in Conforming SMIL 2.0 Documents.
Synchronized Multimedia Integration Language 2.1 does not change that much with regard to that. Previously I claimed that SMIL 2.1 had six different namespaces elements could be in. I was wrong. There are 48 different namespaces SMIL 2.1 elements and attributes can be in. (Given that I counted correctly.) Including SMIL 1.0 and SMIL 2.0 there are 111 different namespaces to choose from. I think I can now safely answer my question with regard to whether or not SMIL is a mess. Leaving alone that it does not integrate well with the DOM et cetera. Given that this is some documentation, here is the full list:
http://www.w3.org/TR/REC-smil
http://www.w3.org/2001/SMIL20/
http://www.w3.org/2001/SMIL20/Language
http://www.w3.org/2001/SMIL20/HostLanguage
http://www.w3.org/2001/SMIL20/IntegrationSet
http://www.w3.org/2001/SMIL20/AccessKeyTiming
http://www.w3.org/2001/SMIL20/AudioLayout
http://www.w3.org/2001/SMIL20/BasicAnimation
http://www.w3.org/2001/SMIL20/BasicContentControl
http://www.w3.org/2001/SMIL20/BasicInlineTiming
http://www.w3.org/2001/SMIL20/BasicLayout
http://www.w3.org/2001/SMIL20/BasicLinking
http://www.w3.org/2001/SMIL20/BasicMedia
http://www.w3.org/2001/SMIL20/BasicTimeContainers
http://www.w3.org/2001/SMIL20/BasicTransitions
http://www.w3.org/2001/SMIL20/BrushMedia
http://www.w3.org/2001/SMIL20/CustomTestAttributes
http://www.w3.org/2001/SMIL20/EventTiming
http://www.w3.org/2001/SMIL20/ExclTimeContainers
http://www.w3.org/2001/SMIL20/FillDefault
http://www.w3.org/2001/SMIL20/HierarchicalLayout
http://www.w3.org/2001/SMIL20/InlineTransitions
http://www.w3.org/2001/SMIL20/LinkingAttributes
http://www.w3.org/2001/SMIL20/MediaAccessibility
http://www.w3.org/2001/SMIL20/MediaClipMarkers
http://www.w3.org/2001/SMIL20/MediaClipping
http://www.w3.org/2001/SMIL20/MediaDescription
http://www.w3.org/2001/SMIL20/MediaMarkerTiming
http://www.w3.org/2001/SMIL20/MediaParam
http://www.w3.org/2001/SMIL20/Metainformation
http://www.w3.org/2001/SMIL20/MinMaxTiming
http://www.w3.org/2001/SMIL20/MultiArcTiming
http://www.w3.org/2001/SMIL20/MultiWindowLayout
http://www.w3.org/2001/SMIL20/ObjectLinking
http://www.w3.org/2001/SMIL20/PrefetchControl
http://www.w3.org/2001/SMIL20/RepeatTiming
http://www.w3.org/2001/SMIL20/RepeatValueTiming
http://www.w3.org/2001/SMIL20/RestartDefault
http://www.w3.org/2001/SMIL20/RestartTiming
http://www.w3.org/2001/SMIL20/SkipContentControl
http://www.w3.org/2001/SMIL20/SplineAnimation
http://www.w3.org/2001/SMIL20/Structure
http://www.w3.org/2001/SMIL20/SyncbaseTiming
http://www.w3.org/2001/SMIL20/SyncBehavior
http://www.w3.org/2001/SMIL20/SyncBehaviorDefault
http://www.w3.org/2001/SMIL20/SyncMaster
http://www.w3.org/2001/SMIL20/TimeContainerAttributes
http://www.w3.org/2001/SMIL20/TimeManipulations
http://www.w3.org/2001/SMIL20/TransitionModifiers
http://www.w3.org/2001/SMIL20/WallclockTiming
http://www.w3.org/2001/SMIL20/NestedTimeContainers
http://www.w3.org/2001/SMIL20/DeprecatedFeatures
http://www.w3.org/2005/SMIL21/
http://www.w3.org/2005/SMIL21/Language
http://www.w3.org/2005/SMIL21/Mobile
http://www.w3.org/2005/SMIL21/ExtendedMobile
http://www.w3.org/2005/SMIL21/HostLanguage
http://www.w3.org/2005/SMIL21/IntegrationSet
http://www.w3.org/2005/SMIL21/AccessKeyTiming
http://www.w3.org/2005/SMIL21/AudioLayout
http://www.w3.org/2005/SMIL21/BackgroundTilingLayout
http://www.w3.org/2005/SMIL21/AlignmentLayout
http://www.w3.org/2005/SMIL21/BasicAnimation
http://www.w3.org/2005/SMIL21/BasicContentControl
http://www.w3.org/2005/SMIL21/BasicInlineTiming
http://www.w3.org/2005/SMIL21/BasicExclTimeContainers
http://www.w3.org/2005/SMIL21/BasicLayout
http://www.w3.org/2005/SMIL21/BasicLinking
http://www.w3.org/2005/SMIL21/BasicMedia
http://www.w3.org/2005/SMIL21/BasicPriorityClassContainers
http://www.w3.org/2005/SMIL21/BasicTimeContainers
http://www.w3.org/2005/SMIL21/BasicTransitions
http://www.w3.org/2005/SMIL21/BrushMedia
http://www.w3.org/2005/SMIL21/CustomTestAttributes
http://www.w3.org/2005/SMIL21/EventTiming
http://www.w3.org/2005/SMIL21/FillDefault
http://www.w3.org/2005/SMIL21/FullScreenTransitionEffects
http://www.w3.org/2005/SMIL21/InlineTransitions
http://www.w3.org/2005/SMIL21/LinkingAttributes
http://www.w3.org/2005/SMIL21/MediaAccessibility
http://www.w3.org/2005/SMIL21/MediaClipMarkers
http://www.w3.org/2005/SMIL21/MediaClipping
http://www.w3.org/2005/SMIL21/MediaDescription
http://www.w3.org/2005/SMIL21/MediaMarkerTiming
http://www.w3.org/2005/SMIL21/MediaParam
http://www.w3.org/2005/SMIL21/Metainformation
http://www.w3.org/2005/SMIL21/MinMaxTiming
http://www.w3.org/2005/SMIL21/MultiArcTiming
http://www.w3.org/2005/SMIL21/MultiWindowLayout
http://www.w3.org/2005/SMIL21/ObjectLinking
http://www.w3.org/2005/SMIL21/OverrideLayout
http://www.w3.org/2005/SMIL21/PrefetchControl
http://www.w3.org/2005/SMIL21/RepeatTiming
http://www.w3.org/2005/SMIL21/RepeatValueTiming
http://www.w3.org/2005/SMIL21/RestartDefault
http://www.w3.org/2005/SMIL21/RestartTiming
http://www.w3.org/2005/SMIL21/SkipContentControl
http://www.w3.org/2005/SMIL21/SplineAnimation
http://www.w3.org/2005/SMIL21/Structure
http://www.w3.org/2005/SMIL21/SubRegionLayout
http://www.w3.org/2005/SMIL21/SyncbaseTiming
http://www.w3.org/2005/SMIL21/SyncBehavior
http://www.w3.org/2005/SMIL21/SyncBehaviorDefault
http://www.w3.org/2005/SMIL21/SyncMaster
http://www.w3.org/2005/SMIL21/TimeContainerAttributes
http://www.w3.org/2005/SMIL21/TimeManipulations
http://www.w3.org/2005/SMIL21/TransitionModifiers
http://www.w3.org/2005/SMIL21/WallclockTiming
http://www.w3.org/2005/SMIL21/NestedTimeContainers
http://www.w3.org/2005/SMIL21/SMIL20DeprecatedFeatures
http://www.w3.org/2005/SMIL21/SMIL10DeprecatedFeatures
Ten namespaces more than HTML element names in HTML 2.0, 3.2, 4.01 and XHTML 1.1 combined.