1<!ENTITY % a SYSTEM "http://example.org/a/a.dtd">
2%a;
3<!ENTITY % b SYSTEM "http://example.org/b/b.dtd">
4%b;
5<!ENTITY % c SYSTEM "http://example.org/c/c.dtd">
6%c;
7<!ELEMENT abc (a, b, c)>
8