This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
I agree with Eric's definition of "strict." There is also a strict version of HTML 4.01. There are two other types of HTML/XHTML: frameset and transitional. Frameset if for when the page uses frames. Transitional is less "strict" than strict. All of the rules are not enforced.