the spec says they can be used for that and you could easily have a server that checks the HTTP Accept if there is no extension. Most likely you need to hyperli

the spec says they can be used for that and you could easily have a server that checks the HTTP Accept if there is no extension. Most likely you need to hyperlink to many of the resources so you're going to need the extension anyway (eg /employees/110.html has an img src="employees/110.jpg") If it's for a programmatic client, not a browser, the HTTP Accept would probably be sufficient.