The value used in the attribute is a proprietary one from Netscape or Internet Explorer.
<img> proprietary attribute value "absmiddle"
See : http://www.w3.org/TR/html4/struct/objects.html#adef-align-IMG
BAD <p><img src="hello.gif" alt="hello" align="absmiddle">hello</p> GOOD ** <p><img src="hello.gif" alt="hello" align="middle"> hello</p> GOOD ** <p><img src="hello.gif" alt="hello" style="vertical-align: middle;"> hello</p> GOOD but COMPLEX <style type="text/css" media="all"> * {padding: 0; margin: 0;} h1, p{margin: 0.5em;} p.flag img, span {vertical-align: middle;display: inline-block;} p.flag span {padding-left: 5px;} </style> ... <p class="flag"><img src="hello.gif" alt="hello"><span>hello</span></p> ...
** Absmiddle and middle do not have exactly the same behavior.
> "absmiddle" align the center of the image with the vertical center of the text next to it.
> "middle" align the center of the image with the bottom of the text next to it.
HTML specification: http://www.w3.org/TR/html4/