<!DOCTYPE doc [
<!ELEMENT doc ((a, b)| (a, c))>
<!ELEMENT a EMPTY>
<!ELEMENT b (#PCDATA)>
<!ELEMENT c (#PCDATA)>
]>
<doc><a/><c> doc is non-deterministic </c></doc>
<!DOCTYPE doc [
<!ELEMENT doc ((a, b)| (a, c))>
<!ELEMENT a EMPTY>
<!ELEMENT b (#PCDATA)>
<!ELEMENT c (#PCDATA)>
]>
<doc><a/><c> doc is non-deterministic </c></doc>