Where should PSGML find standard DTDs?

[Pete Forman]

On upgrading from 21.5.17 to 21.5.28 I found that psgml-dtds has been
deprecated.  My own XML documents where I manage the DTDs are okay.
Standard DTDs such as HTML 4.01 and XHTML 1.0 are no longer available.

What is the recommended config now?  Should I force the psgml-dtds
package to install, or manage all the DTDs in my own area?
-- 
Pete Forman                -./\.-  Disclaimer: This post is originated
WesternGeco                  -./\.-   by myself and does not represent
pete.forman at westerngeco.com    -./\.-   the opinion of Schlumberger or
http://petef.port5.com           -./\.-   WesternGeco.