Appendix D: Conformance Criteria

This appendix is informative, not normative.

D.1 Introduction

Different sets of SVG conformance criteria exist for:

Conforming SVG Documents
Conforming SVG Stand-Alone Files
Conforming SVG Included Documents
Conforming SVG Generators
Conforming SVG Interpreters
Conforming SVG Viewers

D.2 Conforming SVG Documents

An SVG document is a Conforming SVG Document if it adheres to the specification described in this document (Scalable Vector Graphics (SVG) Specification) and also:

is a well-formed XML document
if all non-SVG namespace elements and attributes are removed from the given document, is a valid XML document
conforms to the following W3C Recommendations:
- the XML 1.0 specification (Extensible Markup Language (XML) 1.0)
- (if any namespaces other than SVG are used in the document) Namespaces in XML
- any use of CSS styles and properties needs to conform to Cascading Style Sheets, level 2 CSS2 Specification
- any references to external style sheets should conform to Associating stylesheets with XML documents

D.3 Conforming SVG Stand-Alone Files

A file is a Conforming SVG Stand-Alone File if:

it is a Conforming SVG Document
its outermost XML element is an svg element

D.4 Conforming SVG Included Documents

SVG documents can be included within parent XML documents using the XML namespace facilities described in Namespaces in XML.

An SVG document that is included within a parent XML document is a Conforming Included SVG Document if the SVG document, when taken out of the parent XML document, conforms to the SVG Document Type Definitions (DTD).

In particular, note that individual elements from the SVG namespace cannot be used by themselves. Thus, the SVG part of the following document is not conforming:

<?xml version="1.0" standalone="no"?>
<!DOCTYPE SomeParentXMLGrammar PUBLIC "-//SomeParent" 
  "http://SomeParentXMLGrammar.dtd">
<ParentXML>
  <!-- Elements from ParentXML go here -->

  <!-- The following is not conforming -->
  <z:rect xmlns:z="http://www.w3.org/Graphics/SVG/SVG-19990812.dtd"
            x="0" y="0" width="10" height="10" />

  <!-- More elements from ParentXML go here -->
</ParentXML>

Instead, for the SVG part to become a Conforming Included SVG Document, the file could be modified as follows:

<?xml version="1.0" standalone="no"?>
<!DOCTYPE SomeParentXMLGrammar PUBLIC "-//SomeParent" 
  "http://SomeParentXMLGrammar.dtd">
<ParentXML>
  <!-- Elements from ParentXML go here -->

  <!-- The following is conforming -->
  <z:svg xmlns:z="http://www.w3.org/Graphics/SVG/SVG-19990812.dtd"
         width="100px" height="100px" >
    <z:rect x="0" y="0" width="10" height="10" />
  </z:svg>

  <!-- More elements from ParentXML go here -->
</ParentXML>

D.5 Conforming SVG Generators

A Conforming SVG Generator is a program which:

always creates at least one of Conforming SVG Documents, Conforming SVG Stand-Alone Files or Conforming SVG Included Documents
does not create non-conforming SVG documents of any of the above types
conforms to the SVG accessibility guidelines

SVG generators are encouraged to follow W3C developments in the area of internationalization. Of particular interest is the W3C Character Model and the concept of Webwide Early Uniform Normalization, which promises to enhance the interchangability of Unicode character data across users and applications. Future versions of the SVG Specification are likely to require support of the W3C Character Model in Conforming SVG Generators.

D.6 Conforming SVG Interpreters

An SVG interpreter is a program which can parse and process SVG documents. A Conforming SVG Interpreter must be able to:

Successfully parse and process any Conforming SVG Document, (It is not required, however, that every possible SVG feature be supported beyond parsing. Thus, for example, a Conforming SVG Interpreter might bypass the processing of selected SVG elements.)
If the program allows scripts to run against the SVG document's Document Object Model, then a Conforming SVG Interpreter must support the entire DOM model for SVG defined in this specification
The XML parser must be able to handle arbitrarily long data streams.

D.7 Conforming SVG Viewers

An SVG viewer is a program which can parse and process an SVG document and render the contents of the document onto some sort of output medium such as a display or printer. Usually, an SVG Viewer is also an SVG Interpreter.

Specific criteria for a Conforming SVG Viewer:

In the typical case where the SVG Viewer is also an SVG Interpreter, then the program must also be a Conforming SVG Interpreter,
All SVG features described in this specification (including all graphic elements, attributes and properties) must be supported and rendered.
If display devices are supported, facilities must exist for zooming and panning of standalone SVG documents or SVG documents embedded within parent XML documents.
If printing devices are supported, SVG documents must be printable at printer resolutions with the same graphics features available as required for display (e.g., color must print correctly on color printers).
The viewer should receive enough information from the parent environment to determine the device resolution. (In situations where this information is impossible to determine, the parent environment should pass a reasonable value for device resolution which tends to approximate most common target devices.)
In web browser environments, the viewer must have the ability to search and select text strings within SVG documents.
If display devices are supported, the viewer must have the ability to select and copy text from an SVG document to the system clipboard
The viewer must have complete support for an ECMAScript binding of the SVG Document Object Model.
The viewer must support JPEG and PNG image formats.
The viewer must support alpha channel blending of the SVG document image onto the target canvas.
The viewer must support the following W3C Recommendations with regard to SVG documents:
- complete support for the XML 1.0 specification (Extensible Markup Language (XML) 1.0)
- complete support for inclusion of non-SVG namespaces within an SVG document Namespaces in XML (Note that data from non-SVG namespaces can be ignored.)
- complete support for all features from CSS2 (Cascading Style Sheets, level 2 CSS2 Specification) that are described in this specification as applying to SVG
- complete support for external style sheets as described in Associating stylesheets with XML documents

Although anti-aliasing support isn't a strict requirement for a Conforming SVG Viewer, it is highly recommended. Lack of anti-aliasing support will generally result in poor results on display devices.

A higher class concept is that of a Conforming High-Quality SVG Viewer which must support the following additional features:

Generally, professional-quality results with good processing and rendering performance and smooth, flicker-free animations
On low-resolution devices such as display devices at 150dpi or less, support for smooth edges on lines, curves and text (Smoothing is often accomplished using anti-aliasing techniques.)
Progressive rendering and animation effects (i.e., the start of the document will start appearing and animations will start running in parallel with downloading the rest of the document)
Restricted screen updates (i.e., only required areas of the display are updated in response to redraw events)
Background downloading of images and fonts retrieved from a web server, with updating of the display once the downloads are complete
Color management via ICC profile support (i.e., the ability to support colors defined using ICC profiles)
Resampling of image data using algorithms at least as good as bicubic resampling methods