> thing called HTML which of course was a bit lacking in specification and uniformity at the time. HTML was actually pretty well specified except for one cruci

> thing called HTML which of course was a bit lacking in specification and uniformity at the time. HTML was actually pretty well specified except for one crucial omission: How a user agent should treat invalid HTML. XML simply declared that a user agent should stop processing and report an error - something you can get away with when you don't need to worry about backwards compatibility. Unfortunately this left XHTML dead in the water.