<!ELEMENT doc (elt1|elt2|elt3)*>
<!ELEMENT elt1 (#PCDATA)>
<!ELEMENT elt2 (#PCDATA)>
<!ELEMENT elt3 (#PCDATA)>
<!ENTITY ent1 "[text of ent1]">
<!ENTITY ent2 "[text of ent2]">
<!ENTITY ent3 "[text of ent3]">
<!ENTITY ent4 "[text of ent4]">
<!ENTITY ent5 "[text of ent5]">