Missing Character Entities in HTML Reference

The following entities are missing in the HTML 4.0 reference:

&{"&"}; {javascriptExpression};
&{javascriptVariable};

For example, the following are legal statements in Netscape 4:

<DIV ID=aLayer1 LEFT=&{"&"}; {window.document.aLayer2.left};>
<HR WIDTH="&{barwidth};%" ALIGN=LEFT>

Is it an omission or by design?  If by design, shouldn't the reference indicate that they are reserved?

References:
http://developer.netscape.com/docs/manuals/communicator/dynhtml/layers32.html
http://home.netscape.com/eng/mozilla/3.0/handbook/javascript/getstart.htm

- Michael Gilsdorf