<!ELEMENT Res-list EMPTY>
<!ATTLIST Res-list sources ENTITIES #REQUIRED>
<!NOTATION htm "HTTP 1.1">
<!ENTITY Site1 PUBLIC
"http://www.yahoo.com" NDATA htm>
<!ENTITY Site2 PUBLIC
"http://www.excite.com" NDATA htm >
<!ENTITY Site3 PUBLIC
"http://www.askjeeves.com" NDATA htm >
...
<Res-list sources="&Site1; &Site2; &Site3"/>