[[ Print the folder-and-number line. ]]
"(Message " mf ":" mn $<i ")\n" $+ $+ $+ $+ @outstring

[[ Do any stuff before the bulk of the headers ]]
\prehdrlist
L(
  t?i Lu
  s+ @hdrget t?i ??
    s- "(No " sx ":)\n" $+ $+ @outstring
  ?|
    ": " sx "\n" $+ $+ $+ @outstring
    L(
      s+ @hdrget t?i Lu
      ": " sx "\n" $+ $+ $+ @outstring
    L) s- s-
  ?.
L)
?? "--------\n" @outstring ?.

[[ Line generator.
   Usage: if this is f, then
	f -- f' x
   where f' is the next f and x is the line, or integer if no more.
]]
{
  L(
    "" @hdrget
    t?i ??
      s- s- { 0 } ""
    ?|
      \hdrignore ?? s- s- Lc ?.
      ": " sx $+ $+
    ?. Lb
  L)
}

[[ Call generator until it returns an integer, dumping each line in turn. ]]

L(
  s+ Cc t?i Lu @outstring "\n" @outstring
L)

[[ Clean up the stack. ]]
s- s-

[[ Dump the rest of the message. ]]
@dumpbody