<?xml encoding="ISO-8859-1"?>
<!ELEMENT bib (vendor)*>
<!ELEMENT vendor (name, email, book*)>
<!ATTLIST vendor id ID #REQUIRED>
<!ELEMENT book (title, publisher?, year?, author+, price)>
<!ELEMENT author (firstname?, lastname)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT email (#PCDATA)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT publisher (#PCDATA)>
<!ELEMENT year (#PCDATA)>
<!ELEMENT firstname (#PCDATA)>
<!ELEMENT lastname (#PCDATA)>
<!ELEMENT price (#PCDATA)>