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