Document Structure

Defining an SVG document fragment: the 'svg' element

Overview

An SVG document fragment consists of any number of SVG elements contained within an 'svg' element.

An SVG document fragment can range from an empty fragment (i.e., no content inside of the 'svg' element), to a very simple SVG document fragment containing a single SVG graphics element such as a 'rect', to a complex, deeply nested collection of container elements and graphics elements.

An SVG document fragment can stand by itself as a self-contained file or resource, in which case the SVG document fragment is an SVG document, or it can be embedded inline as a fragment within a parent XML document.

The following example shows simple SVG content embedded inline as a fragment within a parent XML document. Note the use of XML namespaces to indicate that the 'svg' and 'ellipse' elements belong to the SVG namespace:



   
   
      
   
   

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This example shows a slightly more complex (i.e., it contains multiple rectangles) stand-alone, self-contained SVG document:

'svg' elements can appear in the middle of SVG content. This is the mechanism by which SVG document fragments can be embedded within other SVG document fragments.

Another use for 'svg' elements within the middle of SVG content is to establish a new viewport. (See Establishing a new viewport.)

In all cases, for compliance with the Namespaces in XML Recommendation [XML-NS], an SVG namespace declaration must be provided so that all SVG elements are identified as belonging to the SVG namespace. The following are possible ways to provide a namespace declaration. An 'xmlns' attribute without a namespace prefix could be specified on an 'svg' element, which means that SVG is the default namespace for all elements within the scope of the element with the 'xmlns' attribute:


  

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If a namespace prefix is specified on the 'xmlns' attribute (e.g., xmlns:svg="http://www.w3.org/2000/svg"), then the corresponding namespace is not the default namespace, so an explicit namespace prefix must be assigned to the elements:


  

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Namespace prefixes can be specified on ancestor elements (illustrated in the above example). For more information, refer to the Namespaces in XML Recommendation [XML-NS].

This section should talk about how a document's behavior is defined in terms of the DOM, and also explain how the HTML parser can create SVG fragments.

The 'svg' element

SVG 2 Requirement: Should support the playbackOrder attribute to inform UA to not display controls to seek backwards.
Resolution: Support the playbackOrder attribute.
Purpose: To inform UA to not display controls to seek backwards.
Owner: Cyril
SVG 2 Requirement: Support transforming 'svg' elements.
Resolution: We will allow 'transform' on 'svg' in SVG 2.
Purpose: To allow transforms on nested 'svg' elements, in line with author expectations.
Owner: Dirk (no action)
SVG 2 Requirement: Support a means for having SMIL animations start before their time container has fully loaded.
Resolution: Timeline control.
Purpose: To start animations before the SVG document is fully loaded (useful for large SVG documents).
Owner: Cyril

Attribute definitions:

Name Value Lacuna value Animatable
x, y <length> 0 yes

The 'x' and 'y' attributes specify the top-left corner of the rectangular region into which an embedded 'svg' element is placed. On an outermost svg element, these attributes have no effect.

Name Value Lacuna value Animatable
width, height See 'width property' and 'height property' auto yes

Note that 'width' and 'height' are presentation attributes.

For outermost svg elements, the 'width property' and 'height property' attributes specify the intrinsic size of the SVG document fragment. For embedded 'svg' elements, they specify the size of the rectangular region into which the 'svg' element is placed.

A negative value is an error (see Error processing). A value of zero disables rendering of the element.

When zero is used on an outer 'svg' element, does this disable rendering too? Or does it just affect the intrinsic size?

Name Value Lacuna value Animatable
preserveAspectRatio defer? <align> [ meet | slice ]? xMidYMid meet yes

Specifies the fitting behavior when the aspect ratio of the 'svg' element does not match the aspect ratio of the rectangle it is placed in. See the definition of 'preserveAspectRatio' for details.

Name Value Lacuna value Animatable
zoomAndPan disable | magnify magnify no

Specifies whether the user agent should supply a means to zoom and pan the SVG content. See the definition of 'zoomAndPan' for details.

Name Value Lacuna value Animatable
playbackOrder forwardOnly | all all no

This attribute may be harmonized and/or replaced with the work done as part of the Web Animation specification.

Indicates whether it is possible to seek backwards in the document. In earlier versions of SVG there was no need to put restrictions on the direction of seeking but with the newly introduced facilities for long-running documents (e.g. the 'discard' element) there is sometimes a need to restrict this.

If 'playbackOrder' is set to 'forwardOnly', the content will probably contain 'discard' elements or scripts that destroy resources, thus seeking back in the document's timeline may result in missing content. If 'playbackOrder' is 'forwardOnly', the content should not provide a way, through hyperlinking or script, of seeking backwards in the timeline. Similarly the UA should disable any controls it may provide in the user interface for seeking backwards. Content with playbackOrder="forwardOnly" that provides a mechanism for seeking backwards in time may result in undefined behavior or a document that is in error.

Can't we define this so that there is no undefined behavior?

Attribute values have the following meanings:

'forwardOnly'
This file is intended to be played only in the forward direction, sequentially, therefore seeking backwards should not be allowed.
'all'
Indicates that the document is authored appropriately for seeking in both directions.
Name Value Lacuna value Animatable
timelineBegin onLoad | onStart onLoad no

This attribute may be harmonized and/or replaced with the work done as part of the Web Animation specification.

Controls the initialization of the timeline for the document.

The 'svg' element controls the document timeline, which is the timeline of the 'svg' element's time container. For progressively loaded animations, the author would typically set this attribute to 'onStart', thus allowing the timeline to begin as the document loads, rather than waiting until the complete document is loaded.

Attribute values have the following meanings:

'onLoad'
The document's timeline starts the moment the load event for the rootmost 'svg' element is triggered.
'onStart'
The document's timeline starts at the moment the rootmost 'svg' element's start-tag as defined in XML 1.0 ([XML10], section 3.1) is fully parsed and processed.

What about when the SVG document fragment is within an XHTML document? Is there a single timeline for the whole document, and if so, does it start at the parse time for the first <svg> start tag? What about when using the HTML parser?

If an SVG document is likely to be referenced as a component of another document, the author will often want to include a 'viewBox' attribute on the outermost svg element of the referenced document. This attribute provides a convenient way to design SVG documents to scale-to-fit into an arbitrary viewport.

The 'svg' element exposes as event handler content attributes a number of the event handlers of the Window object. It also mirrors their event handler IDL attributes.

The onblur, 'onerror', onfocus, 'onload', and 'onscroll' event handlers of the Window object, exposed on the 'svg' element, replace the generic event handlers with the same names normally supported by SVG elements.

The above paragraphs feel out of place just after the list of attributes specific to 'svg'.

Grouping: the 'g' element

Overview

The 'g' element is a container element for grouping together related graphics elements.

Grouping constructs, when used in conjunction with the 'desc' and 'title' elements, provide information about document structure and semantics. Documents that are rich in structure may be rendered graphically, as speech, or as braille, and thus promote accessibility.

That generously structured content with 'title' and 'desc' is more accessible isn't necessarily true. It also seems like a stretch to claim that documents "rich in structure" can be rendered as speech or braille, without specific references to how that can be achieved. More fundamental uses of grouping that should be mentioned are (a) for specifying common styling of inherited properties, and (b) for selecting elements to apply a group effect like filters and group opacity.

A group of elements, as well as individual objects, can be given a name using the 'id' attribute. Named groups are needed for several purposes such as animation and re-usable objects.

An example:

A 'g' element can contain other 'g' elements nested within it, to an arbitrary depth. Thus, the following is possible:



  Groups can nest
  
     
       
       
     
   

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This is not a particularly useful example.

SVG 2 Requirement: Have unknown elements treated as 'g' for the purpose of rendering.
Resolution: Accept having unknown elements treated as 'g' for the purpose of rendering.
Purpose: To allow fallbacks without the use of 'switch', and to align with the behavior of unknown elements in HTML.
Owner: Nobody (no action)

Any element that is not contained within a 'g' is treated (at least conceptually) as if it were in its own group.

It is unclear what this sentence actually means. Does it mean that all operations that apply to groups (such as group opacity, filter effects, etc.) can apply to single elements too? If so, then it should say that.

The 'g' element

Overview

SVG allows graphical objects to be defined for later reuse. To do this, it makes extensive use of URL references [RFC3987] to these other objects. For example, to fill a rectangle with a linear gradient, you first define a 'linearGradient' element and give it an ID, as in:

...
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You then reference the linear gradient as the value of the 'fill' property for the rectangle, as in:


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Some types of element, such as gradients, will not by themselves produce a graphical result. They can therefore be placed anywhere convenient. However, sometimes it is desired to define a graphical object and prevent it from being directly rendered. it is only there to be referenced elsewhere. To do this, and to allow convenient grouping defined content, SVG provides the 'defs' element.

It is recommended that, wherever possible, referenced elements be defined inside of a 'defs' element. Among the elements that are always referenced: 'clipPath', 'cursor element', 'filter element', 'linearGradient', 'marker element', 'mask element', 'pattern', 'radialGradient' and 'symbol'. Defining these elements inside of a 'defs' element promotes understandability of the SVG content and thus promotes accessibility.

Again this claim about accessibility is dubious.

We should have a term for definition elements (since we now have a corresponding IDL interface) and reference it here.

The 'defs' element

The 'defs' element is a container element for referenced elements. For understandability and accessibility reasons, it is recommended that, whenever possible, referenced elements be defined inside of a 'defs'.

The content model for 'defs' is the same as for the 'g' element; thus, any element that can be a child of a 'g' can also be a child of a 'defs', and vice versa.

Elements that are descendants of a 'defs' are not rendered directly; they are prevented from becoming part of the rendering tree just as if the 'defs' element were a 'g' element and the 'display' property were set to none. Note, however, that the descendants of a 'defs' are always present in the source tree and thus can always be referenced by other elements; thus, the value of the 'display' property on the 'defs' element or any of its descendants does not prevent those elements from being referenced by other elements.

To provide some SVG user agents with an opportunity to implement efficient implementations in streaming environments, creators of SVG content are encouraged to place all elements which are targets of local URL references within a 'defs' element which is a direct child of one of the ancestors of the referencing element. For example:

Is this really about efficiency of implementations? If anything, it looks like it is ensuring progressively rendered documents don't make forward references that would otherwise cause an incorrect rendering before the referenced element is loaded.

In the document above, the linear gradient is defined within a 'defs' element which is the direct child of the 'svg' element, which in turn is an ancestor of the 'rect' element which references the linear gradient. Thus, the above document conforms to the guideline.

The 'discard' element

Would this element be better as part of the Animation chapter? It also needs to be a member of the element categories that other animation elements are, and an IDL interface needs to be written for it.

SVG 2 Requirement: Have the 'discard' element to declaratively discard elements from the document tree.
Resolution: SVG 2 will support the discard element.
Purpose: To conserve memory while displaying long-running documents.
Owner: Cyril (ACTION-3319)

Need to define SVGDiscardElement DOM interface for 'discard' element.

The 'discard' element allows authors to specify the time at which particular elements are to be discarded, thereby reducing the resources required by an SVG user agent. This is particularly useful to help SVG viewers conserve memory while displaying long-running documents. This element will not be processed by static SVG viewers.

The 'discard' element may occur wherever the 'animate' element may.

Attribute definitions:

Name Value Lacuna value Animatable
href <url> (none) no

An URL reference that identifies the target element to discard. See the definition of 'href' on animation elements for details on identifying a target element.

Note that if the target element is not part of the current SVG document fragment then whether the target element will be removed or not is defined by the host language.

If the 'href' attribute is not provided, then the target element will be the immediate parent element of the discard element.

Name Value Lacuna value Animatable
begin <begin-value-list> 0s no

Indicates when the target element will be discarded. See the definition of 'begin' on animation elements for details.

The 'discard' element has an implicit simple duration of "indefinite". As soon as the element's active duration starts, the SVG user agent discards the element identified by the 'href' attribute ([SMIL], section 5.4.5). The removal operation acts as if removeChild were called on the parent of the target element with the target element as parameter. [DOM4] The SVG user agent must remove the target node as well as all of its attributes and descendants.

After removal of the target element, the 'discard' element is no longer useful. It must also be discarded following the target element removal. If the 'href' attribute has an invalid URL reference (the target element did not exist, for example), the 'discard' element itself must still be removed following activation.

Seeking backwards in the timeline ([SMIL], section 5.4.5) must not re-insert the discarded elements. Discarded elements are intended to be completely removed from memory. So, authors are encouraged to set the 'playbackOrder' attribute to "forwardOnly" when using the 'discard' element.

The 'discard' element itself can be discarded prior to its activation, in which case it will never trigger the removal of its own target element. SVG user agents must allow the 'discard' element to be the target of another 'discard' element.

The following example demonstrates a simple usage of the 'discard' element. The list below describes relevant behavior in the document timeline of this example:

At time = 0:
When the document timeline starts, the blue ellipse starts to move down the page.
At time = 1 second:
The red rectangle starts moving up the page.
At time = 2 seconds:
The 'animateTransform' on the 'ellipse' ends. The 'ellipse' and its children are also discarded, as it is the target element of a 'discard' with begin="2". The green 'polygon' starts to move across the page.
At time = 3 seconds:
The animation on the red rectangle ends. The rectangle and its children are discarded as it is the target of a 'discard' element with begin="3".
At time = 4 seconds:
The animation on the green triangle ends. The green 'polygon' and its children are discarded as it is the target of a 'discard' element with begin="4".

The 'desc' and 'title' elements

The attribute 'lang' added to allow internationalization of the 'desc' and 'title element' elements.

Adding 'lang' resolved at Rigi Kaltbad face-to-face. Removed text that limited number of 'desc' and 'title' elements.

Is there any updated wording from SVG Tiny 1.2 that we should be using wrt tooltips?

Each container element or graphics element in an SVG drawing can supply one or more 'desc' and/or one or more 'title' description strings where the description is text-only. When the current SVG document fragment is rendered as SVG on visual media, 'desc' and 'title' elements are not rendered as part of the graphics. User agents may, however, for example, display the 'title' element as a tooltip, as the pointing device moves over particular elements. Alternate presentations are possible, both visual and aural, which display the 'desc' and 'title' elements but do not display 'path' elements or other graphics elements. This is readily achieved by using a different (perhaps user) style sheet. For deep hierarchies, and for following 'use' element references, it is sometimes desirable to allow the user to control how deep they drill down into descriptive text.

I don't think it is easy to use a style sheet to cause an element's 'title' to be rendered in place of its graphics.

More than one 'desc' or 'title element' may be present with different 'lang' attributes. The text displayed will be the text from the element where the 'lang' attribute best matches the language set by the user agent. If no match exists, the text from the first element is used (to allow default text to be given for legacy renderers). If multiple equally valid matches exist, the first match is used.

'lang' should be defined here (rather than pointing to the glyph definition).

The following is an example. In typical operation, the SVG user agent would not render the 'desc' and 'title' elements but would render the remaining contents of the 'g' element.



  
    Company sales by region
    Chiffre d'affaires par région
    Bar chart which shows company sales by region.
    Graphique illustrant les ventes par région.
    
  

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Description and title elements can contain marked-up text from other namespaces. Here is an example:



  
    This is an example SVG file
    The global description uses markup from the 
      mydoc namespace.
  
  
    
  

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We should say what purpose including other-namespaced markup in 'title' and 'desc' has. If it is just that these are basically metadata extension points for other profiles or uses of SVG, then we should say that.

Authors should always provide a 'title' child element to the outermost svg element within a stand-alone SVG document. The 'title' child element to an 'svg' element serves the purposes of identifying the content of the given SVG document fragment. Since users often consult documents out of context, authors should provide context-rich titles. Thus, instead of a title such as "Introduction", which doesn't provide much contextual background, authors should supply a title such as "Introduction to Medieval Bee-Keeping" instead. For reasons of accessibility, user agents should always make the content of the 'title' child element to the outermost svg element available to users. The mechanism for doing so depends on the user agent (e.g., as a caption, spoken).

We have this sentence here about tooltips which is stronger than the earlier note that some implementations do this. We should look at how HTML describes the 'title' attribute and whether a tooltip is required, suggested, etc., and follow that.

Once we have said how ARIA attributes can be used in SVG, we might want to define 'title' and 'desc' in a manner consistent with them, so that it is clear what it means for example for an element to have both a 'desc' element child and an 'aria-describedby' attribute.

The 'symbol' element

The 'symbol' element is used to define graphical template objects which can be instantiated by a 'use' element.

The use of 'symbol' elements for graphics that are used multiple times in the same document adds structure and semantics. Documents that are rich in structure may be rendered graphically, as speech, or as braille, and thus promote accessibility.

Again this mention of accessibility through the use of structure (this time with 'symbol' elements). We should include an example here or in the Accessibility appendix that shows how this is the case and what the actual effects of structuring content with 'symbol' are.

The key distinctions between a 'symbol' and a 'g' are:

Closely related to the 'symbol' element are the 'marker element' and 'pattern' elements.

'symbol' elements are never rendered directly; their only usage is as something that can be referenced using the 'use' element. The 'display' property does not apply to the 'symbol' element; thus, 'symbol' elements are not directly rendered even if the 'display' property is set to a value other than none, and 'symbol' elements are available for referencing even when the 'display' property on the 'symbol' element or any of its ancestors is set to none.

The 'use' element

SVG 2 Requirement: Allow 'use' to reference an external document's root element by omitting the fragment.
Resolution: We will relax referencing requirements to particular elements to allow dropping fragments to mean referencing root element, where it makes sense, such as with use, in SVG 2.
Purpose: To avoid requiring authors to modify the referenced document to add an ID to the root element.
Owner: Cameron (ACTION-3417)

Any 'svg', 'symbol', 'g', graphics element or other 'use' is potentially a template object that can be re-used (i.e., "instanced") in the SVG document via a 'use' element. The 'use' element references another element and indicates that the graphical contents of that element is included/drawn at that given point in the document.

'use' is described as referencing template objects, but the parameters of the template are limited – just different inherited property values.

The 'use' element can reference an entire SVG document by specifying an 'xlink:href' value without a fragment. Such references are taken to be referring to the root element of the referenced document.

This allows an entire SVG document to be referenced without having to ensure that it has an ID on its root element.

The 'use' element has optional attributes 'use/x', 'use/y', 'use/width' and 'use/height' which are used to map the graphical contents of the referenced element onto a rectangular region within the current coordinate system.

The effect of a 'use' element is as if the contents of the referenced element were deeply cloned into a separate non-exposed DOM tree which had the 'use' element as its parent and all of the 'use' element's ancestors as its higher-level ancestors. Because the cloned DOM tree is non-exposed, the SVG Document Object Model (DOM) only contains the 'use' element and its attributes. The SVG DOM does not show the referenced element's contents as children of 'use' element.

We should define the behavior of 'use' in terms of Web Components.

For user agents that support Styling with CSS, the conceptual deep cloning of the referenced element into a non-exposed DOM tree also copies any property values resulting from the CSS cascade ([CSS21], chapter 6) on the referenced element and its contents. CSS2 selectors can be applied to the original (i.e., referenced) elements because they are part of the formal document structure. CSS2 selectors cannot be applied to the (conceptually) cloned DOM tree because its contents are not part of the formal document structure.

We should be requiring CSS styling in SVG 2. Also, hopefully, how styles can apply or not to elements in the shadow tree (and how event handling works, below) should be specified by how we define 'use' to work in terms of Web Components.

Property inheritance, however, works as if the referenced element had been textually included as a deeply cloned child of the 'use' element. The referenced element inherits properties from the 'use' element and the 'use' element's ancestors. An instance of a referenced element does not inherit properties from the referenced element's original parents.

If event attributes are assigned to referenced elements, then the actual target for the event will be the element within the "instance tree" corresponding to the given referenced element.

Should reference Shadow DOM for the event handling. Note that events will be retargeted to maintain the encapsulation, ie. not to leak the original target inside a shadow tree.

The event handling for the non-exposed tree works as if the referenced element had been textually included as a deeply cloned child of the 'use' element, and events are dispatched according to the shadow tree event dispatching algorithm [SHADOWDOM]. The event's target and currentTarget attributes are set to the instance tree element that corresponds to the target and current target elements in the referenced subtree. An event propagates through the exposed and non-exposed portions of the tree in the same manner as it would in the regular document tree: first going from the root element to the 'use' element and then through non-exposed tree elements in the capture phase, followed by the target phase at the target of the event, then bubbling back through non-exposed tree to the use element and then back through regular tree to the root element in bubbling phase. In order to maintain encapsulation events must use the event retargeting algorithm [SHADOWDOM] when crossing from a non-exposed tree to the regular tree.

The behavior of the 'visibility' property conforms to this model of property inheritance. Thus, specifying 'visibility:hidden' on a 'use' element does not guarantee that the referenced content will not be rendered. If the 'use' element specifies 'visibility:hidden' and the element it references specifies 'visibility:hidden' or 'visibility:inherit', then that one element will be hidden. However, if the referenced element instead specifies 'visibility:visible', then that element will be visible even if the 'use' element specifies 'visibility:hidden'.

Why is 'visibility' called out specially? It might be better just to include an example that shows this.

Animations on a referenced element will cause the instances to also be animated.

A 'use' element has the same visual effect as if the 'use' element were replaced by the following generated content:

Except that the replaced content shouldn't affect how styles are matched.

For user agents that support Styling with CSS, the generated 'g' element carries along with it the "cascaded" property values on the 'use' element which result from the CSS cascade ([CSS21], chapter 6). Additionally, the copy (deep clone) of the referenced resource carries along with it the "cascaded" property values resulting from the CSS cascade on the original (i.e., referenced) elements. Thus, the result of various CSS selectors in combination with the 'class' and 'style attribute' attributes are, in effect, replaced by the functional equivalent of a 'style attribute' attribute in the generated content which conveys the "cascaded" property values.

Example Use01 below has a simple 'use' on a 'rect'.

The visual effect would be equivalent to the following document:

Example Use02 below has a 'use' on a 'symbol'.

The visual effect would be equivalent to the following document:

Example Use03 illustrates what happens when a 'use' has a 'transform' property.

The visual effect would be equivalent to the following document:

Example Use04 illustrates a 'use' element with various methods of applying CSS styling.

The visual effect would be equivalent to the following document. Observe that some of the style rules above apply to the generated content (i.e., rules 1-6, 10-12), whereas others do not (i.e., rules 7-9). The rules which do not affect the generated content are:

  • Rules 7 and 8: CSS selectors only apply to the formal document tree, not on the generated tree; thus, these selectors will not yield a match.
  • Rule 9: The generated tree only inherits from the ancestors of the 'use' element and does not inherit from the ancestors of the referenced element; thus, this rule does not affect the generated content.

In the generated content below, the selectors that yield a match have been transferred into inline 'style attribute' attributes for illustrative purposes.

When a 'use' references another element which is another 'use' or whose content contains a 'use' element, then the deep cloning approach described above is recursive. However, a set of references that directly or indirectly reference a element to create a circular dependency is an error, as described in References and the 'defs' element.

Attribute definitions:

Name Value Lacuna value Animatable
x, y <length> 0 yes
width, height <length> (see prose) yes

The 'x', 'y', 'width' and 'height' attributes specify the positioning of the referenced element. The 'width' and 'height' attributes have different lacuna values depending on the type of the referenced element:

'svg'
The lacuna values are the 'svg/width' and 'svg/height' values from the referenced 'svg' element.
anything else
The lacuna values are '100%'.

A negative value for 'width' or 'height' is an error (see Error processing). If 'width' or 'height' is zero then rendering of the 'use' element is disabled.

Name Value Lacuna value Animatable
href <url> (none) yes

An URL reference to the element/fragment within an SVG document to be cloned for rendering.

Conditional processing

Conditional processing overview

SVG contains a 'switch' element along with attributes 'requiredFeatures', 'requiredExtensions' and 'systemLanguage' to provide an ability to specify alternate viewing depending on the capabilities of a given user agent or the user's language.

Attributes 'requiredFeatures', 'requiredExtensions' and 'systemLanguage' act as tests and return either true or false results. The 'switch' renders the first of its children for which all of these attributes test true. If the given attribute is not specified, then a true value is assumed.

It sounds strange to talk about attributes "returning" a value. However it is the test, not the attribute, tat returns a value.

Similar to the 'display' property, conditional processing attributes only affect the direct rendering of elements and do not prevent elements from being successfully referenced by other elements (such as via a 'use').

In consequence:

The 'switch' element

The 'switch' element evaluates the 'requiredFeatures', 'requiredExtensions' and 'systemLanguage' attributes on its direct child elements in order, and then processes and renders the first child for which these attributes evaluate to true. All others will be bypassed and therefore not rendered. If the child element is a container element such as a 'g', then the entire subtree is either processed/rendered or bypassed/not rendered.

Note that the values of properties 'display' and 'visibility' have no effect on 'switch' element processing. In particular, setting 'display' to none on a child of a 'switch' element has no effect on true/false testing associated with 'switch' element processing.

The 'switch' element does not affect processing of 'script' elements.

For more information and an example, see Embedding foreign object types.

The 'requiredFeatures' attribute

Name Value Lacuna value Animatable
requiredFeatures list-of-features (none) no

Need a grammar for list-of-features.

The value is a list of feature strings, with the individual values separated by white space. Determines whether all of the named features are supported by the user agent. Only feature strings defined in the Feature String appendix are allowed. If all of the given features are supported, then the attribute evaluates to true; otherwise, the current element and its children are skipped and thus will not be rendered.

If the attribute is not present, then its implicit return value is "true". If a null string or empty string value is given to attribute 'requiredFeatures', the attribute returns "false".

'requiredFeatures' is often used in conjunction with the 'switch' element. If the 'requiredFeatures' is used in other situations, then it represents a simple switch on the given element whether to render the element or not.

The 'requiredExtensions' attribute

The 'requiredExtensions' attribute defines a list of required language extensions. Language extensions are capabilities within a user agent that go beyond the feature set defined in this specification. Each extension is identified by an URL reference.

Name Value Lacuna value Animatable
requiredExtensions list-of-extensions (none) no

The value is a list of URL references which identify the required extensions, with the individual values separated by white space. Determines whether all of the named extensions are supported by the user agent. If all of the given extensions are supported, then the attribute evaluates to true; otherwise, the current element and its children are skipped and thus will not be rendered.

If a given URL reference contains white space within itself, that white space must be escaped.

If the attribute is not present, then its implicit return value is "true". If a null string or empty string value is given to attribute 'requiredExtensions', the attribute returns "false".

'requiredExtensions' is often used in conjunction with the 'switch' element. If the 'requiredExtensions' is used in other situations, then it represents a simple switch on the given element whether to render the element or not.

The URL names for the extension should include versioning information, such as "http://example.org/SVGExtensionXYZ/1.0", so that script writers can distinguish between different versions of a given extension.

The 'systemLanguage' attribute

The attribute value is a comma-separated list of 'languageID', as defined in BCP 47 [BCP47].

Evaluates to "true" if one of the languages indicated by user preferences exactly equals one of the languages given in the value of this parameter, or if one of the languages indicated by user preferences exactly equals a prefix of one of the languages given in the value of this parameter such that the first tag character following the prefix is "-".

Evaluates to "false" otherwise.

Note: This use of a prefix matching rule does not imply that language tags are assigned to languages in such a way that it is always true that if a user understands a language with a certain tag, then this user will also understand all languages with tags for which this tag is a prefix.

The prefix rule simply allows the use of prefix tags if this is the case.

Implementation note: When making the choice of linguistic preference available to the user, implementers should take into account the fact that users are not familiar with the details of language matching as described above, and should provide appropriate guidance. As an example, users may assume that on selecting "en-gb", they will be served any kind of English document if British English is not available. The user interface for setting user preferences should guide the user to add "en" to get the best matching behavior.

Multiple languages MAY be listed for content that is intended for multiple audiences. For example, content that is presented simultaneously in the original Maori and English versions, would call for:

<text systemLanguage="mi, en"><!-- content goes here --></text>

However, just because multiple languages are present within the object on which the 'systemLanguage' test attribute is placed, this does not mean that it is intended for multiple linguistic audiences. An example would be a beginner's language primer, such as "A First Lesson in Latin," which is clearly intended to be used by an English-literate audience. In this case, the 'systemLanguage' test attribute should only include "en".

Authoring note: Authors should realize that if several alternative language objects are enclosed in a 'switch', and none of them matches, this may lead to situations where no content is displayed. It is thus recommended to include a "catch-all" choice at the end of such a 'switch' which is acceptable in all cases.

For the 'systemLanguage' attribute: Animatable: no.

If the attribute is not present, then its implicit return value is "true". If a null string or empty string value is given to attribute 'systemLanguage', the attribute returns "false".

'systemLanguage' is often used in conjunction with the 'switch' element. If the 'systemLanguage' is used in other situations, then it represents a simple switch on the given element whether to render the element or not.

Should have an attribute definition table in this section.

Applicability of test attributes

The following list describes the applicability of the test attributes to the elements that do not directly produce rendering.

This was already mentioned in the "Conditional processing overview" section. We should just describe this once.

Common attributes

Attributes common to all elements: 'id' and 'xml:base'

The 'id' and 'xml:base' attributes are available on all SVG elements:

Name Value Lacuna value Animatable
id name (none) no

Need a grammar for name.

Standard XML attribute for assigning a unique name to an element. Refer to the Extensible Markup Language (XML) 1.0 Recommendation [XML10].

Name Value Lacuna value Animatable
xml:base <url> (none) no

Specifies a base URL other than the base URL of the document or external entity. Refer to the XML Base specification [XML-BASE].

Are we happy to keep promoting the use of 'xml:base'? Is it a use case worth trying to include a more HTML-like syntax for – the 'base' element? We anyway need to define somewhere what effect the HTML 'base' element has on any SVG document fragments.

The 'xml:lang' attribute

Elements that might contain character data content can have the attribute 'xml:lang'.

SVG 2 Requirement: Deprecate the use of 'xml:space' to affect text layout and use the 'white-space' property instead.
Resolution: We drop xml:space from SVG 2 and remove the relating tests from the SVG 1.1. test suite.
Purpose: To align with CSS.
Owner: Chris (ACTION-3004, done; and ACTION-3005, done)

Should we be moving 'lang'? instead of 'xml:lang'? At minimum allow both lang and xml:lang (then needs a priority if both specified).

Name Value Lacuna value Animatable
xml:lang 'languageID' (none) no

Standard XML attribute to specify the language (e.g., English) used in the contents and attribute values of particular elements. Refer to the Extensible Markup Language (XML) 1.0 Recommendation [XML10].

Name Value Lacuna value Animatable
xml:space default | preserve default no

Deprecated XML attribute to specify whether white space is preserved in character data. The only possible values are 'default' and 'preserve'. Refer to the Extensible Markup Language (XML) 1.0 Recommendation [XML10] and to the discussion white space handling in SVG.

New content should use the 'white-space' property instead.

The 'tabindex' attribute

Name Value Lacuna value Animatable
tabindex <number> (none) no

This content attribute allows authors to control whether an element is focusable, whether it is supposed to be reachable using sequential focus navigation, and what is to be the relative order of the element for the purposes of sequential focus navigation

The name "tab index" comes from the common use of the "tab" key to navigate through the focusable elements. The term "tabbing" refers to moving forward through the focusable elements that can be reached using sequential focus navigation.

WAI-ARIA attributes

Role attribute

SVG elements having native semantics that are not limited to presentation (having "no role"), may have an ARIA role attribute specified. The attribute, if specified, must have a value that is a set of space-separated tokens representing the various WAI-ARIA roles that the element belongs to. These tokens are role values defined in Definition of Roles ([ARIA], section 5.4).

The WAI-ARIA role that an SVG element has assigned to it is the first non-abstract role found in the list of values generated when the role attribute is split on spaces.

Name Value Lacuna value Animatable
role white-space space separated tokens having values defined in Definition of Roles ([ARIA], section 5.4) (see prose) no

The role value is a set of white-space separated machine-extractable semantic information used to define the purpose of the element.

The "Value" entry in the attribute definition box above should be a grammar, not a sentence. Maybe we can define a symbol <role> by reference to the ARIA specification, and then define the attribute as taking "role+".

The lacuna value for the 'role' attribute is the corresponding default implied ARIA semantic for SVG elements.

State and property attributes (all aria- attributes)

SVG elements having native semantics that are not limited to presentation (having "no role"), may have an may have WAI-ARIA state and property attributes specified. These attributes are defined by ARIA in Definitions of States and Properties (all aria-* attributes) ([ARIA], section 6.6).

These attributes, if specified, must have a value that is the WAI-ARIA value type in the "Value" field of the definition for the state or property, mapped to the appropriate SVG value type according to Mapping WAI-ARIA Value types to langauges using the SVG mapping ([ARIA], section 10.2).

WAI-ARIA State and Property attributes can be used on any element. They are not always meaningful, however, and in such cases user agents might not perform any processing aside from including them in the DOM. Unlike some other host languages, SVG is not considered to have strong native host language semantics in terms of the user interface, consequently state and property attributes are processed according to the ARIA and ARIA User Agent Implementation Guide specifications. [ARIA] [ARIAIMPL]

Implicit ARIA Semantics

The following table defines the implicit native semantics and corresponding default implicit ARIA semantics that apply to SVG elements. Each language feature (element) in a cell in the first column implies the ARIA semantics (role, states, and/or properties) given in the cell in the second column of the same row. The third column defines restrictions as to what WAI-ARIA semantic (role, state, or property) may or may not apply.

Language featureDefault implied ARIA semanticsRestrictions
'a' link role no restrictions
'animate' none no role may be applied
'animateMotion' none no role may be applied
'animateTransform' none no role may be appplied
'audio' none If specified, role must be application
'canvas' group role no restrictions
'circle' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'clipPath' none no role may be applied
'cursor element' none no restrictions
'defs' none no role may be applied
'desc' none no role may be applied
'discard' none no role may be applied
'ellipse' none no restrictions
'feBlend' none no role may be applied
'feColorMatrix' none no role may be applied
'feComponentTransfer' none no role may be applied
'feComposite' none no role may be applied
'feConvolveMatrix' none no role may be applied
'feCustom' none no role may be applied
'feDiffuseLighting' none no role may be applied
'feDisplacementMap' none no role may be applied
'feDistantLight' none no role may be applied
'feDropShadow' none no role may be applied
'feFlood' none no role may be applied
'feFuncA' none no role may be applied
'feFuncB' none no role may be applied
'feFuncG' none no role may be applied
'feFuncR' none no role may be applied
'feGaussianBlur' none no role may be applied
'feImage' none no role may be applied
'feMerge' none no role may be applied
'feMergeNode' none no role may be applied
'feMorphology' none no role may be applied
'feOffset' none no role may be applied
'fePointLight' none no role may be applied
'feSpecularLighting' none no role may be applied
'feSpotLight' none no role may be applied
'feTile' none no role may be applied
'feTurbulence' none no role may be applied
'filter element' none no role may be applied
'foreignObject' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'g' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'hatch' none no role may be applied
'hatchPath' none no role may be applied
'iframe' no role If Specified, role must be either application, document, or img roles
'image' img role no restrictions
'line' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'linearGradient' none no role may be applied
'marker element' none no role may be applied
'mask element' none no role may be applied
'meshGradient' none no role may be applied
'meshPatch' none no role may be applied
'meshRow' none no role may be applied
'metadata' none no role may be applied
'mpath' none no role may be applied
'path' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'pattern' none no role may be applied
'polygon' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'polyline' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'radialGradient' none no role may be applied
'rect' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'script' none no role may be applied
'set' none no role may be applied
'solidColor' none no role may be applied
'source' none no role may be applied
'stop' none no role may be applied
'style element' none no role may be applied
'svg' group role no restrictions
'switch' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'symbol' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'text' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'textPath' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'title' none no role may be applied
'track' none no role may be applied
'tspan' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'use' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions
'video' none If specified, role must be application
'view' presentation role provided no associated 'title' element, 'desc' element, 'aria-label' attribute, 'aria-labelledby' attribute, or 'aria-describedby' attribute; otherwise, group role no restrictions

DOM interfaces

Interface Document

The DOM Core specification defines a Document interface, which this specification extends.

In the case where an SVG document is embedded by reference, such as when an HTML document has an 'object' element whose 'href' attribute references an SVG document (i.e., a document whose MIME type is "image/svg+xml" and whose root element is thus an 'svg' element), there will exist two distinct DOM hierarchies. The first DOM hierarchy will be for the referencing document (e.g., an XHTML document). The second DOM hierarchy will be for the referenced SVG document.

For historical reasons, Window objects must also have a writable, configurable, non-enumerable property named SVGDocument whose value is the Document interface object.

partial interface Document {
  readonly attribute SVGSVGElement rootElement;
};
Attributes:
rootElement (readonly SVGSVGElement)
The root 'svg' in the document hierarchy.

This attribute is deprecated, and may be removed in a future SVG specification. Authors are encouraged to use the documentElement attribute on Document instead.

The following IDL fragment must be supported only if the SVG implementation is also a Web browser or other interactive user agent, and therefore implements HTML.

// must only be implemented in certain implementations
partial interface Document {
  readonly attribute DOMString title;
  readonly attribute DOMString referrer;
  readonly attribute DOMString domain;
  readonly attribute Element? activeElement;
};

This is because the interface members below are already defined in HTML, and in implementations that support SVG and HTML we they cannot be duplicated.

The title, referrer, domain and activeElement IDL attributes must behave the same as the corresponding IDL attributes defined in HTML.

Issues have been filed on HTML so that title and activeElement work on SVG documents (by looking at 'title' elements in the SVG namespace, and by defaulting to the root 'svg' element rather than the body element, respectively).

Interface SVGSVGElement

A key interface definition is the SVGSVGElement interface, which is the interface that corresponds to the 'svg' element. This interface contains various miscellaneous commonly-used utility methods, such as matrix operations and the ability to control the time of redraw on visual rendering devices.

SVGSVGElement implements ViewCSS and DocumentCSS to provide access to the computed values of properties and the override style sheet as described in DOM Level 2 Style [DOM2STYLE].

Does it make sense for SVGSVGElement to implement ViewCSS and DocumentCSS? Shouldn't the former be on Window and the latter on Document or SVGDocument?

interface SVGSVGElement : SVGGraphicsElement {

  readonly attribute SVGAnimatedLength x;
  readonly attribute SVGAnimatedLength y;
  readonly attribute SVGAnimatedLength width;
  readonly attribute SVGAnimatedLength height;
  readonly attribute DOMRectReadOnly viewport;
  readonly attribute float pixelUnitToMillimeterX;
  readonly attribute float pixelUnitToMillimeterY;
  readonly attribute float screenPixelToMillimeterX;
  readonly attribute float screenPixelToMillimeterY;
  readonly attribute boolean useCurrentView;
  readonly attribute SVGViewSpec currentView;
           attribute float currentScale;
  readonly attribute DOMPointReadOnly currentTranslate;

  unsigned long suspendRedraw(unsigned long maxWaitMilliseconds);
  void unsuspendRedraw(unsigned long suspendHandleID);
  void unsuspendRedrawAll();
  void forceRedraw();
  void pauseAnimations();
  void unpauseAnimations();
  boolean animationsPaused();
  float getCurrentTime();
  void setCurrentTime(float seconds);
  NodeList getIntersectionList(DOMRectReadOnly rect, SVGElement referenceElement);
  NodeList getEnclosureList(DOMRectReadOnly rect, SVGElement referenceElement);
  boolean checkIntersection(SVGElement element, DOMRectReadOnly rect);
  boolean checkEnclosure(SVGElement element, DOMRectReadOnly rect);
  void deselectAll();
  SVGNumber createSVGNumber();
  SVGLength createSVGLength();
  SVGAngle createSVGAngle();
  DOMPoint createSVGPoint();
  DOMMatrix createSVGMatrix();
  DOMRect createSVGRect();
  SVGTransform createSVGTransform();
  SVGTransform createSVGTransformFromMatrix(DOMMatrixReadOnly matrix);
  Element getElementById(DOMString elementId);
};

SVGSVGElement implements ViewCSS;
SVGSVGElement implements DocumentCSS;
SVGSVGElement implements SVGFitToViewBox;
SVGSVGElement implements SVGZoomAndPan;
SVGSVGElement implements WindowEventHandlers;
Attributes:
x (readonly SVGAnimatedLength)
Corresponds to attribute 'x' on the given 'svg' element.
y (readonly SVGAnimatedLength)
Corresponds to attribute 'y' on the given 'svg' element.
width (readonly SVGAnimatedLength)
Corresponds to attribute 'width' on the given 'svg' element.

What value should be returned here (since this is now a presentation attribute)?

height (readonly SVGAnimatedLength)
Corresponds to attribute 'height' on the given 'svg' element.

What value should be returned here (since this is now a presentation attribute)?

viewport (readonly DOMRectReadOnly)

The position and size of the viewport (implicit or explicit) that corresponds to this 'svg' element. When the user agent is actually rendering the content, then the position and size values represent the actual values when rendering. The position and size values are unitless values in the coordinate system of the parent element. If no parent element exists (i.e., 'svg' element represents the root of the document tree), if this SVG document is embedded as part of another document (e.g., via the HTML 'object' element), then the position and size are unitless values in the coordinate system of the parent document. (If the parent uses CSS or XSL layout, then unitless values represent pixel units for the current CSS or XSL viewport, as described in the CSS2 specification.) If the parent element does not have a coordinate system, then the user agent should provide reasonable default values for this attribute.

The DOMRectReadOnly object is read only.

pixelUnitToMillimeterX (readonly float)
Size of a pixel units (as defined by CSS2) along the x-axis of the viewport, which represents a unit somewhere in the range of 70dpi to 120dpi, and, on systems that support this, might actually match the characteristics of the target medium. On systems where it is impossible to know the size of a pixel, a suitable default pixel size is provided.

Should this and the next three IDL attributes be removed? Are they implemented?

pixelUnitToMillimeterY (readonly float)
Corresponding size of a pixel unit along the y-axis of the viewport.
screenPixelToMillimeterX (readonly float)
User interface (UI) events in DOM Level 2 indicate the screen positions at which the given UI event occurred. When the user agent actually knows the physical size of a "screen unit", this attribute will express that information; otherwise, user agents will provide a suitable default value such as .28mm.
screenPixelToMillimeterY (readonly float)
Corresponding size of a screen pixel along the y-axis of the viewport.
useCurrentView (readonly boolean)
The initial view (i.e., before magnification and panning) of the current innermost SVG document fragment can be either the "standard" view (i.e., based on attributes on the 'svg' element such as 'svg/viewBox') or to a "custom" view (i.e., a hyperlink into a particular 'view' or other element - see Linking into SVG content: URL fragments and SVG views). If the initial view is the "standard" view, then this attribute is false. If the initial view is a "custom" view, then this attribute is true.
currentView (readonly SVGViewSpec)

The definition of the initial view (i.e., before magnification and panning) of the current innermost SVG document fragment. The meaning depends on the situation:

The object itself and its contents are both read only.

currentScale (float)
On an outermost svg element, this attribute indicates the current scale factor relative to the initial view to take into account user magnification and panning operations, as described under Magnification and panning. DOM attributes currentScale and currentTranslate are equivalent to the 2x3 matrix [a b c d e f] = [currentScale 0 0 currentScale currentTranslate.x currentTranslate.y]. If "magnification" is enabled (i.e., zoomAndPan="magnify"), then the effect is as if an extra transformation were placed at the outermost level on the SVG document fragment (i.e., outside the outermost svg element).

The value of a transform property on the outermost svg element does not affect the value of this attribute.

When accessed on an 'svg' element that is not an outermost svg element, this attribute must return 1 as scaling factor.

currentTranslate (readonly DOMPointReadOnly)
On an outermost svg element, the corresponding translation factor that takes into account user "magnification".

The value of a transform property on the outermost svg element does not affect the value of this attribute.

When accessed on an 'svg' element that is not an outermost svg element, this attribute must return an DOMPointReadOnly at the coordinates (0, 0).

Operations:
unsigned long suspendRedraw(unsigned long maxWaitMilliseconds)
This method is deprecated, and is only kept due to compatibility with legacy content. Calling this method has no effect on redrawing.
Parameters
  1. unsigned long maxWaitMilliseconds
    This parameter is ignored.
Returns
The returned value is always 1.
void unsuspendRedraw(unsigned long suspendHandleID)
This method is deprecated, and is only kept due to compatibility with legacy content. Calling this method has no effect on redrawing.
Parameters
  1. unsigned long suspendHandleID
    This parameter is ignored.
void unsuspendRedrawAll()
This method is deprecated, and is only kept due to compatibility with legacy content. Calling this method has no effect on redrawing.
void forceRedraw()
In rendering environments supporting interactivity, forces the user agent to immediately redraw all regions of the viewport that require updating.

Should this method be neutered as suspendRedraw and friends have been? Do implementations actually support painting in the middle of a running script by calling this method?

void pauseAnimations()
Suspends (i.e., pauses) all currently running animations that are defined within the SVG document fragment corresponding to this 'svg' element, causing the animation clock corresponding to this document fragment to stand still until it is unpaused.
void unpauseAnimations()
Unsuspends (i.e., unpauses) currently running animations that are defined within the SVG document fragment, causing the animation clock to continue from the time at which it was suspended.
boolean animationsPaused()
Returns true if this SVG document fragment is in a paused state.
Returns
Boolean indicating whether this SVG document fragment is in a paused state.
float getCurrentTime()
Returns the current time in seconds relative to the start time for the current SVG document fragment. If getCurrentTime is called before the document timeline has begun (for example, by script running in a 'script' element before the document's load event is dispatched), then 0 is returned.
Returns
The current time in seconds, or 0 if the document timeline has not yet begun.
void setCurrentTime(float seconds)
Adjusts the clock for this SVG document fragment, establishing a new current time. If setCurrentTime is called before the document timeline has begun (for example, by script running in a 'script' element before the document's load event is dispatched), then the value of seconds in the last invocation of the method gives the time that the document will seek to once the document timeline has begun.
Parameters
  1. float seconds
    The new current time in seconds relative to the start time for the current SVG document fragment.
NodeList getIntersectionList(DOMRectReadOnly rect, SVGElement referenceElement)
Returns the list of graphics elements whose rendered content intersects the supplied rectangle. Each candidate graphics element is to be considered a match only if the same graphics element can be a target of pointer events as defined in 'pointer-events' processing.
Parameters
  1. The test rectangle. The values are in the initial coordinate system for the current 'svg' element.
  2. SVGElement referenceElement
    If not null, then any intersected element that doesn't have the referenceElement as ancestor must not be included in the returned NodeList.
Returns
A list of Elements whose content intersects the supplied rectangle. The NodeList that is returned is static ([DOM4], section 5.2.7).
NodeList getEnclosureList(DOMRectReadOnly rect, SVGElement referenceElement)
Returns the list of graphics elements whose rendered content is entirely contained within the supplied rectangle. Each candidate graphics element is to be considered a match only if the same graphics element can be a target of pointer events as defined in 'pointer-events' processing.
Parameters
  1. The test rectangle. The values are in the initial coordinate system for the current 'svg' element.
  2. SVGElement referenceElement
    If not null, then any intersected element that doesn't have the referenceElement as ancestor must not be included in the returned NodeList.
Returns
A list of Elements whose content is enclosed by the supplied rectangle. The NodeList that is returned is static ([DOM4], section 5.2.7).
boolean checkIntersection(SVGElement element, DOMRectReadOnly rect)
Returns true if the rendered content of the given element intersects the supplied rectangle. Each candidate graphics element is to be considered a match only if the same graphics element can be a target of pointer events as defined in 'pointer-events' processing.
Parameters
  1. SVGElement element
    The element on which to perform the given test.
  2. The test rectangle. The values are in the initial coordinate system for the current 'svg' element.
Returns
True or false, depending on whether the given element intersects the supplied rectangle.
boolean checkEnclosure(SVGElement element, DOMRectReadOnly rect)
Returns true if the rendered content of the given element is entirely contained within the supplied rectangle. Each candidate graphics element is to be considered a match only if the same graphics element can be a target of pointer events as defined in 'pointer-events' processing.
Parameters
  1. SVGElement element
    The element on which to perform the given test.
  2. The test rectangle. The values are in the initial coordinate system for the current 'svg' element.
Returns
True or false, depending on whether the given element is enclosed by the supplied rectangle.
void deselectAll()
Unselects any selected objects, including any selections of text strings and type-in bars.

What is a type-in bar? Do we need deselectAll given we have DOM Selection?

SVGNumber createSVGNumber()
Creates an SVGNumber object outside of any document trees. The object is initialized to a value of zero.
Returns
An SVGNumber object.
SVGLength createSVGLength()
Creates an SVGLength object outside of any document trees. The object is initialized to the value of 0 user units.
Returns
An SVGLength object.
SVGAngle createSVGAngle()
Creates an SVGAngle object outside of any document trees. The object is initialized to the value 0 degrees (unitless).
Returns
An SVGAngle object.
DOMPoint createSVGPoint()
Creates an DOMPoint object outside of any document trees. The object is initialized to the point (0,0) in the user coordinate system.
Returns
An DOMPoint object.
DOMMatrix createSVGMatrix()
Creates an DOMMatrix object outside of any document trees. The object is initialized to the identity matrix.
Returns
An DOMMatrix object.
DOMRect createSVGRect()
Creates an DOMRect object outside of any document trees. The object is initialized such that all values are set to 0 user units.
Returns
An DOMRect object.
SVGTransform createSVGTransform()
Creates an SVGTransform object outside of any document trees. The object is initialized to an identity matrix transform (SVG_TRANSFORM_MATRIX).
Returns
An SVGTransform object.
SVGTransform createSVGTransformFromMatrix(DOMMatrixReadOnly matrix)

Creates an SVGTransform object outside of any document trees. The object is initialized to the given matrix transform (i.e., SVG_TRANSFORM_MATRIX). The values from the parameter matrix are copied, the matrix parameter is not adopted as SVGTransform::matrix.

Parameters
  1. The transform matrix.
Returns
An SVGTransform object.
Element getElementById(DOMString elementId)
Searches this SVG document fragment (i.e., the search is restricted to a subset of the document tree) for an Element whose id is given by elementId. If an Element is found, that Element is returned. If no such element exists, returns null. Behavior is not defined if more than one element has this id.

Do we need this? If so, can we define it in terms of calling Document.getElementById and checking whether the returned element is within the subtree?

Parameters
  1. DOMString elementId
    The unique id value for an element.
Returns
The matching element.

Interface SVGGElement

The SVGSVGElement interface corresponds to the 'g' element.
interface SVGGElement : SVGGraphicsElement {
};

Interface SVGDefsElement

The SVGDefsElement interface corresponds to the 'defs' element.
interface SVGDefsElement : SVGGraphicsElement {
};

Interface SVGDescElement

The SVGDescElement interface corresponds to the 'desc' element.
interface SVGDescElement : SVGElement {
};

Interface SVGTitleElement

The SVGTitleElement interface corresponds to the 'title' element.
interface SVGTitleElement : SVGElement {
};

Interface SVGSymbolElement

The SVGSymbolElement interface corresponds to the 'symbol' element.
interface SVGSymbolElement : SVGElement {
};

SVGSymbolElement implements SVGFitToViewBox;

Interface SVGUseElement

The SVGUseElement interface corresponds to the 'use' element.

interface SVGUseElement : SVGGraphicsElement {
  readonly attribute SVGAnimatedLength x;
  readonly attribute SVGAnimatedLength y;
  readonly attribute SVGAnimatedLength width;
  readonly attribute SVGAnimatedLength height;
};

SVGUseElement implements SVGURIReference;
Attributes:
x (readonly SVGAnimatedLength)
Corresponds to attribute 'x' on the given 'use' element.
y (readonly SVGAnimatedLength)
Corresponds to attribute 'y' on the given 'use' element.
width (readonly SVGAnimatedLength)
Corresponds to attribute 'width' on the given 'use' element.
height (readonly SVGAnimatedLength)
Corresponds to attribute 'height' on the given 'use' element.

Interface SVGSwitchElement

The SVGSwitchElement interface corresponds to the 'switch' element.
interface SVGSwitchElement : SVGGraphicsElement {
};

Interface GetSVGDocument

This interface provides access to an SVG document embedded by reference in another DOM-based language. The expectation is that the interface is implemented on DOM objects that allow such SVG document references, such as the DOM Element object that corresponds to an HTML 'object' element. Such DOM objects are often also required to implement the EmbeddingElement defined in the Window specification [WINDOW].

This interface is deprecated and may be dropped from future versions of the SVG specification. Authors are suggested to use the contentDocument attribute on the EmbeddingElement interface to obtain a referenced SVG document, if that interface is available.

[NoInterfaceObject]
interface GetSVGDocument {
  SVGDocument getSVGDocument();
};
Operations:
SVGDocument getSVGDocument()

This method must return the Document object embedded content in an embedding element, or null if there is no document.

Note that this is equivalent to fetching the value of the EmbeddingElement::contentDocument attribute of the embedding element, if the EmbeddingElement interface is also implemented. The author is advised to check that the document element of the returned Document is indeed an 'svg' element instead of assuming that that will always be the case.

Returns
The Document object for the referenced document, or null if there is no document.