accessibility: svg degrading to gif, using embed?

How does one provide alternative images with embed*?
sorry if this is a duffers question, however I'm becoming concerned at the 
apparent lack of interest in accessibility being demonstrated in the various 
svg groups.

*using object we have: 
http://www.siliconpublishing.org/svgfaq/Starting.asp

<object type="image/svg+xml" data="./mjr-svgopenwindow.svg" NAME="owMain" 
width="400" height="150" ></object>
Yes, but put something useful inside the object (that's why it has separate 
start and end tags, unlike img) - a JPEG file, or a text description, or 
both. This will be displayed by systems that can't yet display SVG. 

-- 
jonathan chetwynd

http://www.peepo.com "have fun surfing the net"
http://www.learningdifficulty.org