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