Width attribute on table element

Hello!

I’d like to make a request regarding the width tribute on the table element. It kind of surprises me that only percent values are allowed according to e.g. http://www.docbook.org/tdg5/en/html/html.table.html

I’d like to suggest that other units should be allowed too, namely em, px and pt. Is there any particular reason to only allow percent values?

Thank you!

/frank