.......... not just in standard Graphical Browsers -- MSIE, Firefox, Opera, Safari, Konqueror, et al but also in Text only Browsers - Lynx, Yellowpipe, etc. and Screen Readers - JAWS, etc. I cover this in detail at Interoperability for Web pages James
Screen readers and other assistive devices are not browsers. They're assistive technologies that sit on top of the user agent. You also forgot to mention mobile user agents as well.
Let us not get too pedantic here. I didn't refer to "Screen Readers" as "Browsers" and I employed "Browser" for "Text Only/Textual" because that is what they are frequently called in even authoratative technical treatises. I used the term "The great majority of User Agents" deliberately to exclude external User Agents because I was addressing "on screen" implementations. All are de-facto User Agents as defined by the W3C.