16 Backwards Compatibility

A user agent (UA) might not have the ability to process and view SVG documents. The following list outlines two of the backwards compatibility scenarios associated with SVG documents:

For XML grammars with the ability to embed SVG documents, it is assumed that some sort of alternate representation capability such as the <switch> element and some sort of feature-availability test facility (such as what is described in the SMIL 1.0 specification (??? add links)) will be available.
This <switch> element and feature-availability test facility (or their equivalents) are the recommended way for XML authors to provide an alternate representation to an SVG document, such as an image or a text string. The following example shows how to embed an SVG drawing within a SMIL 1.0 document such that an alternate image will display in the event the UA doesn't support SVG. (In this example, the SVG document is included via a URL reference. With some parent XML grammars it will also be possible to include an SVG document inline within the same file as its parent grammar.)
```
<?xml version="1.0" standalone="yes"?>
<smil>
  <body>
    
    <switch>
      
      <ref system-required="http://www.w3.org/Graphics/SVG/svg-19990730.dtd" 
           type="image/svg" src="drawing.svg" />
      
      <img src="alternate_image.jpg" />
    </switch>
  </body>
</smil>
```
Download this example
For HTML 4.0, SVG drawings should be embedded using the <object> element. The alternate representation should be included as the content of the <object> element. In this case, the SVG document usually will be included via a URL reference. The following example shows how to use the <object> element to include an SVG drawing via a URL reference with an image serving as the alternate representation in the absence of an SVG user agent:
```
<html>
  <body>
    <object type="image/svg" data="drawing.svg">
      
      <img src="alternate_image.jpg" alt="short description" />
    </object>
  </body>
</html>
```