Why does this validate?

From: Richard Savill (dreklind@btinternet.com)
Date: Fri, Sep 24 1999


Date: Fri, 24 Sep 1999 17:25:42 -0400 (EDT)
Message-ID: <002b01bf06d3$1ead4040$95e4abc3@default>
From: "Richard Savill" <dreklind@btinternet.com>
To: <www-validator@w3.org>
Subject: Why does this validate?

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Untitled</title>
</head>
<body>
<table summary="a_test_of_TD_width_att">
<tr>
<td width="OK_buddy_I_want_50%_width">Test</td>
</tr>
</table>
</body>
</html>

Result:

Below are the results of attempting to parse this document with an SGML
parser.

    No errors found!
 Congratulations, this document validates as HTML 4.0 Transitional!

-----------------

Most obvious is that the parser doesn't recognise the 'blahblahblah' in the
quotes.

Second, in any case, percentage is illegal according to even the
transitional DTD. I can't find where percentage is allowed here. Maybe I'm
reading it wrong.

Yet people use %, and render it in browsers. What's the deal here?

Richard Savill
The Jazz Age Page
www.btinternet.com/~dreklind/Jazzhome.htm