previous   next   contents  

2. The SMIL 3.0 Modules

Thierry MICHEL, W3C.

Table of contents

2.1 Introduction

This section is informative.

Since the publication of SMIL 1.0 [SMIL10], interest in the integration of SMIL concepts with the HTML, the HyperText Markup Language [HTML4], and other XML languages, has grown. Likewise, the W3C HTML Working Group has specified XHTML, the Extensible HyperText Markup Language [XHTML10], in preparation to subset, extend, and integrate it with other languages. The strategy considered for integrating respective functionality with other XML-based languages is based on the concepts of modularization and profiling [SMIL-MOD], [XMOD].

Modularization is an approach in which markup functionality is specified as a set of modules that contain semantically-related XML elements, attributes, and attribute values. Profiling is the creation of an XML-based language through combining these modules, in order to provide the functionality required by a particular application.

Profiling introduces the ability to tailor an XML-based language to specific needs, e.g. to optimize presentation and interaction for the client's capabilities. Profiling also adds the ability for integrating functionality from other markup languages, releasing the language designer from specifying that functionality. Moreover, it provides for consistency in markup through the use of the same model to incorporate a function. Identical constructs ease authoring, while at the user agent side there is a potential for re-use of code. For example, a scheduler supporting SMIL timing and synchronization functionality could be used for SMIL documents, XHTML+SMIL documents, and SVG documents.

Modularization enables language designers to specify dedicated markup intended for integration with other, existing, profiles. Examples of specifications intended for such integration are MathML and XForms [MathML], [XFORMS10].

Modularization and profiling use the extensibility properties of XML, and related technology like XML namespaces and XML Schema [XML11], [XML-NS], [XSCHEMA].

This part of the SMIL 3.0 specification describes the framework on which SMIL modularization and profiling is based, and specifies the SMIL 3.0 Modules, their identifiers, and the requirements for conformance within this framework.

2.2 Modularization and Profiling

This section is informative.

The modularization approach used in this specification derives from that set forth in XHTML Modularization [XMOD]. The framework on which SMIL modularization and profiling is based, is informally described here.

A Module is a collection of semantically-related XML elements, attributes, and attribute values that represents a unit of functionality. Modules are defined in coherent sets.

A Profile is a combination of modules. Modules are atomic, i.e. they may not be subset when included in a profile. Furthermore, a module specification may include a set of integration requirements, to which profiles that include the module must comply.

Commonly, there is a main profile that incorporates nearly all the modules associated with a single namespace. For this version of SMIL, this is the SMIL 3.0 Language profile.

Other profiles may be specified that are subsets of the larger one, or that incorporate a mixture of modules associated with different namespaces. SMIL 3.0 Tiny is an example of the first, XHTML+SMIL of the latter.

Several of SMIL's modules define features that that characterize the core of the functionality provided by SMIL. This is expressed by the notions of host language and integration set. Both of them relate to a set of conformance requirements for language profiles, which includes the requirement to incorporate at least the core set of modules. The set may be different for a host language and an integration set. A host language must incorporate the Structure module; an integration set need not. There may be other differences as well.

The main purpose of profile conformance is to enhance interoperability. Preferably, the mandatory modules for host language conformance are defined in such a way that any document interchanged in a conforming profile will yield a reasonable presentation when the document renderer, while supporting the associated mandatory module set, would ignore all other (unknown) elements and attributes. Here, "reasonable presentation" is to be understood as something intelligible, which is not necessarily a close reflection of the author's original intentions. To achieve the latter, a negotiation would have to be conducted to agree on the specific profile to be used for the document interchange.

2.3 Summary of Changes for the SMIL 3.0 Modules

This section is informative.

SMIL 3.0 specification provides three classes of changes to the SMIL 2.1 Recommendation, among the functional areas;

  1. New Modules are introduced (e.g. the MediaPanZoom module, MediaOpacity, BasicText, TextStyling, TextMotion; StateTest, UserState, StateSubmission, StateInterpolation; StructureLayout modules and DOMTimingMethods.
  2. Former SMIL Modules are revised allowing extended functionalities (example are Metainformation, BasicLayout, MediaParam modules).
  3. Former SMIL Modules are unchanged; the modules, elements and attributes semantics remain the same as in SMIL2.1 [SMIL21]. There are no major changes to the modules; apart from minor issues related to typos, links and references.

The following functional areas are affected by SMIL 3.0:


Content Control

This functional area is currently unchanged, apart from repartitioning of the content control module structure in order to support the SMIL Tiny profile. In a future version the content control mechanisms specified will be modified to better align with the expression and test logic being developed within the SMIL 3.0 State modules.


SMIL 3.0 extends the Layout capabilities as follows:


SMIL 3.0 linking integrates the general features of the XHTML-2 access and role attributes as an extension and replacement for the accessKey attribute.

Media Object


This new smilText functionality provides a new media type for use in SMIL presentations. The smilText modules provide a text container element with an explicit content model for defining in-line text, and a set of additional elements and attributes to control explicit in-line text rendering.

The following 3 modules are introduced in the new Text functional area allowing use of in-line text content:

In addition, SMIL 3.0 also defines the smilText profile, which allows timed text markup to be placed in a light-weight external container.


Metainformation mechanisms in SMIL 3.0 provide a general purpose approach to attaching metainformation to any element within the presentation.


The new Identity module identifies the SMIL version and the SMIL profile. This replaces the former SMIL approach of defining separate namespaces for individual modules and profiles.


The SMIL 3.0 specification leaves the basic syntax and semantics of the SMIL 2.1 timing model [SMIL21-timing] unchanged apart from the following changes:


The new modules in this section provide a mechanism whereby the document author may create more complex controlflow than what SMIL provides through the timing and content control modules, without having to go all the way of using a scripting language. One way to provide this is to allow a document to have some explicit state (think: variables) along with ways to modify, use and save this state.

The following 4 modules are introduced in the State functional areas:

2.4 SMIL 3.0 Modules

This section is normative.

SMIL functionality is partitioned into 12 functional areas. Within each functional area a further partitioning is applied into modules. All of these modules, and only these modules, are associated with the SMIL namespace.

The functional areas and their corresponding modules are:

Note: Modules marked with (**) are new Modules added in SMIL 3.0. Modules marked with (*) are revised modules from SMIL 2.1.

  1. Animation
    1. BasicAnimation
    2. SplineAnimation
  2. Content Control
    1. BasicContentControl
    2. CustomTestAttributes
    3. PrefetchControl
    4. RequiredContentControl (**)
    5. SkipContentControl
  3. Layout
    1. AlignmentLayout
    2. AudioLayout
    3. BackgroundTilingLayout
    4. BasicLayout (*)
    5. MultiWindowLayout
    6. OverrideLayout
    7. StructureLayout (**)
    8. SubRegionLayout
  4. Linking
    1. BasicLinking
    2. LinkingAttributes
    3. ObjectLinking
  5. Media Objects
    1. BasicMedia
    2. BrushMedia
    3. MediaAccessibility
    4. MediaClipping
    5. MediaClipMarkers
    6. MediaDescription
    7. MediaOpacity (**)
    8. MediaPanZoom (**)
    9. MediaParam (*)
    10. MediaRenderAttributes(**)
  6. SmilText
    1. BasicText (**)
    2. TextStyling(**)
    3. TextMotion (**)
  7. Metainformation
    1. Metainformation (*)
  8. Structure
    1. Structure
    2. Identity (**)
  9. Timing
    1. AccessKeyTiming
    2. BasicInlineTiming
    3. BasicTimeContainers
    4. BasicExclTimeContainers
    5. BasicPriorityClassContainers
    6. DOMTimingMethods (**)
    7. EventTiming
    8. FillDefault
    9. MediaMarkerTiming
    10. MinMaxTiming
    11. MultiArcTiming
    12. RepeatTiming
    13. RepeatValueTiming
    14. RestartDefault
    15. RestartTiming
    16. SyncbaseTiming
    17. SyncBehavior
    18. SyncBehaviorDefault
    19. SyncMaster
    20. TimeContainerAttributes
    21. WallclockTiming
  10. Time Manipulations
    1. TimeManipulations
  11. State
    1. StateTest (**)
    2. UserState (**)
    3. StateSubmission (**)
    4. StateInterpolation (**)
  12. Transitions
    1. BasicTransitions
    2. InlineTransitions
    3. TransitionModifiers
    4. FullScreenTransitionEffects

Each of these modules introduces a set of semantically-related elements, properties, and attributes. Each functional area has a corresponding section in this specification document. Further details on each of the modules is specified within those sections.

The modules may be independent or complementary. For example, the SyncMaster module requires and builds upon the SyncBehavior module, but the PrefetchControl and SkipContentControl modules are independent from each other. In addition, some modules require modules from other functional areas.

Modules specify their integration requirements. When one module requires another module for basic features and as a prerequisite for integration, a profile must include the second module in order to include the first. The first module is said to be a dependent of the second module. Dependency may be nested, in that a module may be dependent on a module that is a dependent itself.

Table 1 presents the SMIL 3.0 modules and the modules they depend on.

Table 1: The SMIL 3.0 Modules and their Dependencies.
Module Dependencies
AccessKeyTiming NONE
AlignmentLayout BasicLayout
AudioLayout BasicLayout
BackgroundTilingLayout BasicLayout
BasicAnimation BasicInlineTiming
BasicContentControl NONE
BasicInlineTiming NONE
BasicExclTimeContainers NONE
BasicLayout StructureLayout
BasicLinking NONE
BasicMedia NONE
BasicPriorityClassContainers BasicExclTimeContiners
BasicText NONE
BasicTimeContainers NONE
BasicTransitions NONE
BrushMedia NONE
CustomTestAttributes BasicContentControl
DOMTimingMethods NONE
EventTiming NONE
FillDefault BasicTimeContainers, and/or BasicExclTimeContainers, BasicPriorityClassContainers, and/or TimeContainerAttributes
FullScreenTransitionEffects BasicTransitions
Identity NONE
InlineTransitions NONE
LinkingAttributes NONE
MediaAccessibility MediaDescription
MediaClipMarkers MediaClipping
MediaClipping BasicMedia
MediaDescription NONE
MediaMarkerTiming NONE
MediaOpacity BasicMedia
MediaPanZoom BasicMedia
MediaParam BasicMedia
MediaRenderAtrributes NONE
MetaInformation NONE
MinMaxTiming NONE
MultiArcTiming AccessKeyTiming, and/or BasicInlineTiming, and/or EventTiming, and/or
MediaMarkerTiming, and/or RepeatValueTiming, and/or
SyncbaseTiming, and/or WallclockTiming
MultiWindowLayout BasicLayout
ObjectLinking BasicLinking
OverrideLayout BasicLayout, SubRegionLayout
PrefetchControl NONE
RepeatTiming NONE
RepeatValueTiming NONE
RequiredContentControl NONE
RestartDefault RestartTiming
RestartTiming NONE
SkipContentControl NONE
SplineAnimation BasicAnimation
StateInterpolation NONE
StateSubmission UserState
StateTest NONE
Structure BasicContentControl, and BasicInlineTiming, and BasicLayout, and
BasicLinking, and BasicMedia, and BasicTimeContainers, and
SkipContentControl, and SyncbaseTiming
StructureLayout Structure
SubRegionLayout BasicLayout
SyncbaseTiming NONE
SyncBehavior BasicTimeContainers, and/or
BasicExclTimeContainers, BasicPriorityClassContainers, and/or
SyncBehaviorDefault SyncBehavior
SyncMaster SyncBehavior
TextMotion BasicText
TextStyling BasicText
TimeContainerAttributes NONE
TimeManipulations NONE
TransitionModifiers BasicTransitions, and/or InlineTransitions
UserState NONE
WallclockTiming NONE

2.5 Identifiers for SMIL 3.0 MIME Type and the SMIL 3.0 Modules

This section is normative.

This section specifies the identifiers for the SMIL 3.0 MIME Type and the SMIL 3.0 modules. The identifiers for SMIL 3.0 profiles are defined as part of the profile specification.

2.5.1 The SMIL Mime Type

Documents authored in host-language conformant profiles may be associated with the "application/smil+xml" mime type: "application/smil+xml" mime type are required to be host language conformant. The "application/smil" mime type as specified in SMIL 2.0 [SMIL20] is obsolete.

2.5.2 Identifiers for SMIL 3.0 Modules

Each module in this specification has a unique identifier associated with it. They are intended to uniquely and consistently identify each of them. They should be used as values in a test for whether an implementation includes a specific module, as well as in other circumstances where a need to refer to a specific SMIL 3.0 module is necessary. These identifiers are to be used with the systemRequired attribute from the RequiredContentControl module.

Table 2 summarizes the identifiers for SMIL 3.0 modules.

Table 2: The SMIL 3.0 Module Identifiers.
Module name Identifier

2.5.3 Identifiers for SMIL 3.0 Profiles and Features

In addition to the module identifiers above, there are different sets of features that may be expressed using the following identifiers:
Profile allows nesting of the par and seq time containers.
Profile supports deprecated SMIL SMIL 2.0 features.
Profile supports deprecated SMIL 1.0 features.

Modules may also be identified collectively. When grouped into SMIL 3.0 profiles, the module identification string is placed in the profile specification. Profiles will also provide an identification string for their DTD specification. In addition, the following general module collections are defined:
All the modules specified by the SMIL 3.0 specification.
The modules required for SMIL Host Language Conformance.
The modules required for SMIL Integration Set Conformance.

Implementations must allow these as identifiers for use with the systemRequired attribute from the RequiredContentControl module.

Profiles must identify those attributes for which an implementation must return "true" (this is an integration requirement). Implementations must return "false" for modules or features which are not fully supported.

2.6 SMIL Conformance

This section is normative.

The rules for host-language and SMIL 3.0 document conformance, as well as the rules for SMIL 3.0 User Agent conformance are provided as part of the SMIL Scalability Framework.

2.7 Creating a DTD for a SMIL 3.0 Profile

This section is informative.

This section describes how profiles could be defined using the SMIL 3.0 modular DTDs. The reader is assumed to be familiar with the mechanisms defined in "Modularization of XHTML" [XMOD], in particular Appendix D [XMOD-APPD] and Appendix E [XMOD-APPE]. In general, the SMIL 3.0 modular DTDs use the same mechanisms as the XHTML modular DTDs use. Exceptions to this are:

  1. SMIL supports qualified attribute names for SMIL attributes that may appear on non-SMIL elements. This enables these attributes to use prefixes to indicate that they belong to the SMIL 3.0 namespace.
  2. SMIL supports module level INCLUDE/IGNORE instead of XHTML's element/attlist level. Similar to XHTML Modularization, this prohibits profiles from importing only part of a module -- they have to support either all the elements and attributes or none.

Below, we give a short description of the files that are used to define the SMIL 3.0 modular DTDs. See the table and the end of the section for a complete list of the filenames involved.

Following the same mechanisms as the XHTML modular DTDs, the SMIL 3.0 specification places the XML element declarations (e.g. <!ELEMENT...>) and attribute list declarations (e.g. <!ATTLIST...>) of all SMIL 3.0 elements in separate files, the SMIL module files. A SMIL module file is provided for each functional area in the SMIL 3.0 specification (that is, there is a SMIL module file for animation, layout, timing, etc).

The SMIL module files are used in the normative definitions of the specification of the SMIL 3.0 Language profile. Usage of the same module files for defining other SMIL profiles is recommended, but not required. The requirements that SMIL profiles must follow are stated in the SMIL 3.0 specification, not in the DTD code.

To make the SMIL module files independent of each other, and independent of the profiles, the element and attribute declarations make heavy use of XML entities. This provides profiles with the necessary hooks to define the actual content models and attributes of the SMIL elements.

The SMIL 3.0 Language profile provides examples of how the SMIL module files may be used. Most of the DTD files are reused across the different profiles. Reused are the SMIL module files, the files that define the data types and the common attributes, the "qname" file that takes care of adding namespace prefixes if necessary, and the framework file, which takes care of including files in the appropriate order.

The file that is different for each profile is the driver file, and possibly the document model file. To define a new profile, one has to write the extension module(s), the driver file that defines which modules are used, and a document model file that defines the extended document model. A new profile that merely reuses SMIL 3.0 modules may not need a new document model file. The driver file and document model file are described in more detail below.

The driver file.

This is the file that would be referenced by a document's DOCTYPE declaration. Its main job is to define the modules and features that are included in the DTD. The file contains the following parts.

The document model file.

The document model file contains the XML entities that are used by the SMIL module files to define the content models and attribute lists of the elements in that profile.

Content models generally differ from profile to profile, or contain elements from other modules. To avoid these dependencies in the SMIL module files, content models may be defined in the document model file. The (dummy) default content model as defined in the SMIL module files is "EMPTY" for all SMIL 3.0 elements.

For the same reasons, the SMIL module files only define a default attribute list for their elements. This default list only contains the SMIL 3.0 core attributes and the attributes that are defined in the same SMIL module file. All other attributes may be added to this default list by defining the appropriate XML entities. For example, the Media Objects Module file only adds the core and media related attributes on the media objects; other attributes, such as the timing attributes, are added to this list by the document model file.

Table 7: Formal public identifiers and system identifiers of all files used in the SMIL 3.0 modular DTDs.
Driver files for the predefined profiles
-//W3C//DTD SMIL 3.0 Language//EN
-//W3C//DTD SMIL 3.0 Unified Mobile//EN
-//W3C//DTD SMIL 3.0 Daisy//EN
-//W3C//DTD SMIL 3.0 Tiny//EN
-//W3C//DTD SMIL 3.0 smilText//EN
Document model files for the predefined profiles
-//W3C//ENTITIES SMIL 3.0 Document Model 1.0//EN
SMIL 3.0 module files
-//W3C//ELEMENTS SMIL 3.0 Animation//EN
-//W3C//ELEMENTS SMIL 3.0 Content Control//EN
-//W3C//ELEMENTS SMIL 3.0 Layout//EN
-//W3C//ELEMENTS SMIL 3.0 Linking//EN
-//W3C//ELEMENTS SMIL 3.0 Media Objects//EN
-//W3C//ELEMENTS SMIL 3.0 Document Metainformation//EN
-//W3C//ELEMENTS SMIL 3.0 State//EN
-//W3C//ELEMENTS SMIL 3.0 Document Structure//EN
-//W3C//ELEMENTS SMIL 3.0 Timesheet//EN
-//W3C//ELEMENTS SMIL 3.0 Timing//EN
-//W3C//ELEMENTS SMIL 3.0 Transition//EN
Other utilities: data types, common attributes, qname and frame work files
-//W3C//ENTITIES SMIL 3.0 Common Attributes 1.0//EN
-//W3C//ENTITIES SMIL 3.0 Datatypes 1.0//EN
-//W3C//ENTITIES SMIL 3.0 Modular Framework 1.0//EN
-//W3C//ENTITIES SMIL 3.0 Qualified Names 1.0//EN

previous   next   contents