+% #2 is the \...x control sequence (which our caller defines).
+% #3 is the control sequence to process the header, such as \defunheader.
+%
+\def\parsebodycommon#1#2#3{%
+ \begingroup\inENV
+ % If there are two @def commands in a row, we'll have a \nobreak,
+ % which is there to keep the function description together with its
+ % header. But if there's nothing but headers, we want to allow a
+ % break after all.
+ \ifnum\lastpenalty = 10000 \penalty0 \fi
+ \medbreak
+ %
+ % Define the \E... end token that this defining construct specifies
+ % so that it will exit this group.
+ \def#1{\endgraf\endgroup\medbreak}%
+ %
+ \parindent=0in
+ \advance\leftskip by \defbodyindent
+ \exdentamount=\defbodyindent
+}
+
+% Process body of @defun, @deffn, @defmac, etc.
+%
+\def\defparsebody#1#2#3{%
+ \parsebodycommon{#1}{#2}{#3}%
+ \def#2{\begingroup\obeylines\activeparens\spacesplit#3}%
+ \catcode61=\active % 61 is `='
+ \begingroup\obeylines\activeparens
+ \spacesplit#3%
+}
+
+% #1, #2, #3 are the common arguments (see \defparsebody).