Lasthead section in a longtabu environment

Question

Longtable environment has sections for first head and other head. I want to add third section for last head which must be on the last page of a table with slightly different text. Is it possible?

PS. I'm not sure if this question needs minimal working example.

Answer 1

(Some explanation is written in the answer of Configure long table caption

It is possible. Take a look at the following code from longtable.sty

\def\LT@output{%
  \ifnum\outputpenalty <-\@Mi%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \ifnum\outputpenalty > -\LT@end@pen
      \LT@err{floats and marginpars not allowed in a longtable}\@ehc
    \else
      \setbox\z@\vbox{\unvbox\@cclv}%
      \ifdim \ht\LT@lastfoot>\ht\LT@foot
        \dimen@\pagegoal
        \advance\dimen@-\ht\LT@lastfoot
        \ifdim\dimen@<\ht\z@
          \setbox\@cclv\vbox{\unvbox\z@\copy\LT@foot\vss}%
          \@makecol
          \@outputpage
          \setbox\z@\vbox{\box\LT@head}%
        \fi
      \fi
      \global\@colroom\@colht
      \global\vsize\@colht
      \vbox
        {\unvbox\z@\box\ifvoid\LT@lastfoot\LT@foot\else\LT@lastfoot\fi}%
    \fi
  \else
    \setbox\@cclv\vbox{\unvbox\@cclv\copy\LT@foot\vss}%
    \@makecol
    \@outputpage
      \global\vsize\@colroom
    \copy\LT@head\nobreak%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  \fi}

We could see that \ifnum\outputpenalty <-\@Mi is used to check whether this page is the last page. So we would like to \copy\LT@lasthead at this point. However, at this moment \LT@head is already inserted at the top of \@cclv. (Otherwise checking penalty does not make sense.) Therefore we need \setbox\LT@head=\vsplit\@cclv to0pt to remove \LT@head from \@cclv. (And return it back to \LT@head). But this fails since \LT@head in \@cclv follows a \nobreak. So we have to modify the line \copy\LT@head\nobreak to get the following code:

\documentclass{article}
\usepackage{longtable,setspace}
\begin{document}
\listoftables
\setstretch{5}
\makeatletter
\newif\ifmorethanonepage\morethanonepagefalse
\newbox\LT@lasthead\def\endlasthead{\LT@end@hd@ft\LT@lasthead}
\def\LT@output{%
  \ifnum\outputpenalty <-\@Mi
    \ifmorethanonepage\copy\LT@lasthead\fi%%%%%
    \setbox\LT@head=\vsplit\@cclv to0pt%%%%%%
    \ifnum\outputpenalty > -\LT@end@pen
      \LT@err{floats and marginpars not allowed in a longtable}\@ehc
    \else
      \setbox\z@\vbox{\unvbox\@cclv}%
      \ifdim \ht\LT@lastfoot>\ht\LT@foot
        \dimen@\pagegoal
        \advance\dimen@-\ht\LT@lastfoot
        \ifdim\dimen@<\ht\z@
          \setbox\@cclv\vbox{\unvbox\z@\copy\LT@foot\vss}%
          \@makecol
          \@outputpage
          \setbox\z@\vbox{\box\LT@lasthead}%
        \fi
      \fi
      \global\@colroom\@colht
      \global\vsize\@colht
      \vbox
        {\unvbox\z@\box\ifvoid\LT@lastfoot\LT@foot\else\LT@lastfoot\fi}%
    \fi
  \else
    \global\morethanonepagetrue%
    \setbox\@cclv\vbox{\unvbox\@cclv\copy\LT@foot\vss}%
    \@makecol
    \@outputpage
      \global\vsize\@colroom
    \copy\LT@head%%%%%\nobreak
  \fi}
\makeatother
\begin{longtable}{ccc}
    \caption{FIRST} \\\endfirsthead
    \caption{OTHER} \\\endhead
    \caption{LAST} \\\endlasthead
    1 \\ 2 \\ 3 \\ 4 \\ 5 \\ 6 \\ 7 \\ 8 \\ 9 \\ 10 \\ 11 \\ 12 \\ 13 \\ 14 \\ 15 \\ 16 \\ 17 \\ 18 \\ 19 \\ 20 \\ 21 \\ 22 \\ 23 \\ 24 \\ 25 \\ 26 \\ 27 \\ 28 \\ 29 \\ 30 \\ \end{longtable}
\end{document}