<!DOCTYPE doc [
<!ELEMENT doc (a , b)*>
<!ELEMENT a (#PCDATA)>
<!ELEMENT b (#PCDATA)>
]>
<doc><a>This</a><b> is a valid document</b></doc>
<!DOCTYPE doc [
<!ELEMENT doc (a , b)*>
<!ELEMENT a (#PCDATA)>
<!ELEMENT b (#PCDATA)>
]>
<doc><a>This</a><b> is a valid document</b></doc>