1<!DOCTYPE doc [
2<!ATTLIST doc attrExtEnt ENTITY #IMPLIED>
3<!ENTITY ent1 "Hello">
4<!ENTITY ent2 SYSTEM "world.txt">
5<!ENTITY entExt SYSTEM "earth.gif" NDATA gif>
6<!NOTATION gif SYSTEM "viewgif.exe">
7]>
8<doc attrExtEnt="entExt">
9   &ent1;, &ent2;!
10</doc>
11
12<!-- Let world.txt contain "world" (excluding the quotes) -->
13