An aside: Mike's second example doesn't look like it should work, e.g. one wouldn't expect the SAS Macro Facility to resolve the &path variable inside of the single quotes. But since these lie within double quotes, the macro facility sees the single quotes as plain-old characters and not single quotes and DOES resolve the &path variable within.
html = "href='&path./summary_bu.htm'";
put 'HTML: ' html;
(snip snip)
HTML: href='http://domapp.com/Applications/AS/CZ/03de670ff5/$FILE/summary_bu.htm'