1 <!DOCTYPE doc [

     2 <!ELEMENT doc (e)>

     3 <!ELEMENT e (#PCDATA)>

     4 <!ATTLIST e

     5   a1 CDATA "a1 default"

     6   a2 NMTOKENS "a2 default"

     7 >

     8 <!ENTITY x SYSTEM "013.ent">

     9 ]>

    10 <doc>&x;</doc>