<!DOCTYPE doc [ <!ELEMENT doc (#PCDATA | ns:a | ns:b)*> <!ATTLIST doc

attr  CDATA #REQUIRED
xmlns:ns CDATA #IMPLIED>

<!ELEMENT a EMPTY> <!ELEMENT b (#PCDATA)> ]> <ns:doc ns:attr=β€œval” xmlns:ns=β€œwww.example.org/test/”>

<ns:a/>
<ns:b>first line</ns:b>
<ns:b>second line</ns:b>

</ns:doc>