<?xml version="1.1"?>
<!-- Second-level external general entity has later version number than
     first-level, but not later than document, so not an error. -->
<!DOCTYPE foo [
<!ELEMENT foo ANY>
<!ENTITY ent1 SYSTEM "006_1.ent">
<!ENTITY ent2 SYSTEM "006_2.ent">
]>
<foo>&ent1;</foo>