Recently, Sam Ruby announced that the Atom 0.3 syndication format would be deprecated by the Feed Validator. When I first read his post I half wondered what would happen if someone complained about being told their previously valid feed was no longer valid simply because it was now using an "old" format. This afternoon I found an  email from Donald Knuth (yes, that one) to the mailing list complaining about just that. In his mail note from Prof Knuth, he writes

Dear Validators,

I've been happily using your service for many years --- even before w3c
took it over. I've had a collection of web pages at Stanford since
1995 or so; it now amounts to hundreds of pages, dozens of which have
tens of thousands of hits, several of which have hits in the millions.

Every time I make a nontrivial change, I've been asking the validator
to approve it. And every time, I've won the right to display the
"HaL HTML Netscape checked" logo.

Until today. Alluva sudden you guys have jerked the rug out from
under my feet.

I protest! I feel like screaming! Unfair!

I'm not accustomed to flaming, but I have to warn you that I am just
now more than a little hot under the collar and trying not to explode.

For years and years, I have started each webpage with the formula
I found in the book from which I learned HTML many years ago, namely
  <!DOCTYPE HTML PUBLIC "-//Netscape Comm. Corp.//DTD HTML//EN">

Today when I tried to validate a simple edit of one page, I found
that your system no longer is happy --- indeed, it hates every
one of my webpages. (If you need a URL, Google for "don" and take
the topmost page, unless you are in France.)

For example, it now finds 19 errors on my home page, which was 100%
valid earlier this month. The first error is "unknown parse mode!".
Apparently Stanford's Apache server is sending the page out as text/html.
You are saying text/html is ambiguous, but that you are going to continue
as if it were SGML mode. Fine; but if I get the Stanford folks to
change the MIME type to SGML mode, I'll still have 18 more errors.

The next error is "no DOCTYPE found". But guys, it is there as
plain as day. Henceforth you default to HTML 4.01 Transitional.

Then you complain that I don't give "alt" specifications with
any of the images. But the Netscape DTD I have used for more
than 3000 days does not require it.

Then you don't allow align="absmiddle" in an image.

I went to your help page trying to find another DTD that might
suit. Version 2.0 seemed promising; but no, it failed in other
ways --- like it doesn't know the bgcolor and text color attributes
in the <body> of my page.

Look folks, I know that software rot (sometimes called "progress")
keeps growing, and backwards compatibility is not always possible.
At one point I changed my TeX78 system to TeX82 and refused to
support the older conventions.

But in this case I see absolutely no reason why system people who
are supposedly committed to helping the world's users from all
the various cultures are suddenly blasting me in the face and
telling me that you no longer support things that every decent
browser understands perfectly well.

To change all these pages will cost me a week's time. I don't
want to delay The Art of Computer Programming by an unnecessary week;
I've been working on it for 43 years and I have 20 more years of work
to do, and who knows what illnesses and other tragedies are in store.
Every week is precious, especially when it seems to me that there
is no valid validation reason for a competent computer system person
to be so fascistic. For all I know, you'll be making me spend
another week on this next year, and another the year after that.

So, my former friends, please tell me either (i) when you are
going to fix the problem, or (ii) who is your boss so that I
can complain at a higher level.

Excuse me, that was a bit flamey wasn't it, and certainly egocentric.
But I think you understand why I might be upset.

Sincerely, Don Knuth