<!ELEMENT bookshelf	(books) >
<!ELEMENT books	(book+) >
<!ELEMENT book (isbn, title, subtitle?, writer+, publisher, about?, lcc?, dewey?, status?) >
<!ATTLIST book id CDATA #IMPLIED >
<!ATTLIST book href CDATA #IMPLIED >
<!ELEMENT isbn (#PCDATA) >
<!ELEMENT title	(#PCDATA) >
<!ELEMENT subtitle (#PCDATA) >
<!ELEMENT writer (#PCDATA) >
<!ATTLIST writer id CDATA #IMPLIED >
<!ATTLIST writer role (author|editor|foreword|revised|with) "author">
<!ELEMENT publisher (#PCDATA) >
<!ATTLIST publisher id CDATA #REQUIRED >
<!ATTLIST publisher date CDATA #REQUIRED >
<!ATTLIST publisher href CDATA #IMPLIED >
<!ELEMENT about (#PCDATA) >
<!ELEMENT lcc (#PCDATA) >
<!ELEMENT dewey (#PCDATA) >
<!ELEMENT status (#PCDATA) >