(This is a preliminary DTD - Data Type
Definition. It is not strictly correct)
<!ELEMENT
argument (author?,premise)>
<!ELEMENT
author (#PCDATA)>
<!ELEMENT
comment (#PCDATA)>
<!ELEMENT
premise
(title,comment?,(reason|objection|helper)*)>
<!ELEMENT title
(#PCDATA)>
<!ELEMENT
reason
(title,comment?,(reason|objection|helper)*)>
<!ELEMENT
objection
(title,comment?,(reason|objection|helper)*)>
<!ELEMENT
helper
(title,comment?,(reason|objection|helper)*)>