<?xml version="1.0" encoding="UTF-8"?>
<doctype>
  <externalId name="e1" system="054.ent"/>
  <externalIdRef name="e1">
    <element>
      <name>doc</name>
      <elementRef>
        <name>foo</name>
      </elementRef>
    </element>
  </externalIdRef>
  <externalId name="e2" system="sub/054.ent"/>
  <externalIdRef name="e2">
    <element>
      <name>foo</name>
      <sequence/>
    </element>
  </externalIdRef>
</doctype>
