+ <list><item>
+ An OSN text:
+ <newline/><ebnf>
+ <prod of="text"/> <def/>
+ <star/> <prod of="q-expr"/>
+ <stop/>
+ </ebnf>
+ </item></list>
+ <list><item>
+ A qualified symbolic expression:
+ <newline/><ebnf>
+ <prod of="q-expr"/> <def/>
+ <star/> <open/>
+ <prod of="symbol"/> <and/> <plus/> <prod of="sep"/>
+ <close/> <and/>
+ <prod of="expr"/>
+ <stop/>
+ </ebnf>
+ </item></list>
+ <list><item>
+ An unqualified symbolic expression:
+ <newline/><ebnf>
+ <prod of="expr"/> <def/>
+ <prod of="symbol"/> <or/>
+ <prod of="string"/> <or/>
+ <prod of="string-alt"/> <or/>
+ <open/>
+ <prod of="open"/> <and/>
+ <prod of="text"/> <and/>
+ <prod of="close"/>
+ <close/>
+ <stop/>
+ </ebnf>
+ </item></list>
+
+ <section1 name="semantics">Semantics</section1>