\unprotect

% a new variable for horizontal (default) direction

\startvariables            dutch                     english
                           german                    czech
                           italian                   romanian
                           french

               horizontal: horizontal                horizontal
                           horizontal                horizontal
                           horizontal                horizontal
                           horizontal

\stopvariables

% we extract the combine macros from the core

\def\docombinepages[#1][#2]% a=perpag b=free
  {\bgroup
   \dontcomplain
   \getfiguredimensions[#1]%
   \getparameters
     [\??ip]
     [\c!alternative=\v!a,
      \c!n=\noffigurepages,\c!nx=2,\c!ny=2,\c!start=1,\c!stop=\!!maxcard,
      \c!distance=\bodyfontsize,
      \c!bottom=\vfill,\c!top=\vss,
      \c!left=\hss,\c!right=\hss,
      \c!before=\page,\c!after=\page,\c!inbetween=\blank,
      \c!frame=,\c!background=,\c!backgroundcolor=,
      \c!direction=\v!horizontal,
      #2]%
   \@@ipbefore
  %\doglobal\newcounter\combinedpagescounter
   \globallet\combinedpagescounter\@@ipstart
   \doifelse\@@ipalternative\v!b\!!doneafalse\!!doneatrue
   \doifelse\@@ipdirection\v!horizontal\docombinepageshorizontal\docombinepagesvertical#1 % watch the #1 ;-)
   \@@ipafter
   \egroup}

% we work from left to right and from top to bottom

\def\docombinepageshorizontal#1
  {\if!!donea
     \doloop
       {\vbox to \textheight
           {\hsize\textwidth % ? ?
            \scratchdimen\@@ipdistance
            \!!widtha \dimexpr(\hsize-\@@ipnx\scratchdimen+\scratchdimen)/\@@ipnx\relax
            \!!heighta\dimexpr(\vsize-\@@ipny\scratchdimen+\scratchdimen)/\@@ipny\relax
            \dorecurse\@@ipny
              {\hbox to \hsize
                 {\dorecurse\@@ipnx
                    {\vbox to \!!heighta
                       {\hsize\!!widtha
                        \vsize\!!heighta
                        \@@iptop
                        \hbox to \hsize
                          {\@@ipleft
                           \ifnum\combinedpagescounter>\@@ipstop\relax
                             \globallet\@@ipn\!!zerocount
                           \else\ifnum\combinedpagescounter>\@@ipn \else
                             \externalfigure[#1]
                               [\c!object=\v!no,
                                \c!page=\combinedpagescounter,
                                \c!factor=\v!max,
                                \c!background=\@@ipbackground,
                                \c!backgroundcolor=\@@ipbackgroundcolor,
                                \c!frame=\@@ipframe]%
                           \fi\fi
                           \@@ipright}
                        \@@ipbottom}%
                     \doglobal\increment\combinedpagescounter
                     \hfil}%
                  \hfilneg}
               \vfil}%
           \vfilneg}%
           \page
        \ifnum\combinedpagescounter>\@@ipn \exitloop\fi}
   \else
     \doloop
       {\startbaselinecorrection
          \scratchdimen\@@ipdistance
          \!!widtha\dimexpr(\hsize-\@@ipnx\scratchdimen+\scratchdimen)/\@@ipnx\relax
          \hbox to \hsize
            {\dorecurse\@@ipnx
               {\doglobal\increment\combinedpagescounter
                \ifnum\combinedpagescounter>\@@ipn \else
                   \expanded{\externalfigure[#1]
                     [\c!page=\combinedpagescounter,
                      \c!width=\the\!!widtha,% todo \freezedimenmacro
                      \c!background=\@@ipbackground,
                      \c!backgroundcolor=\@@ipbackgroundcolor,
                      \c!frame=\@@ipframe]}%
                   \hfill
                \fi}\hfillneg}%
        \stopbaselinecorrection
        \ifnum\combinedpagescounter<\@@ipn\relax
          \@@ipinbetween
        \else
          \exitloop
        \fi}
   \fi}

% we work from top to bottom and from left to right, no alternative=b

\def\docombinepagesvertical#1
  {\doloop
     {\vbox %to \textheight % neccesary?
        {\hsize\textwidth
         \vsize\textheight
         \scratchdimen\@@ipdistance
         \!!widtha \dimexpr(\hsize-\@@ipnx\scratchdimen+\scratchdimen)/\@@ipnx\relax
         \!!heighta\dimexpr(\vsize-\@@ipny\scratchdimen+\scratchdimen)/\@@ipny\relax
         \hbox to \hsize
           {\dorecurse\@@ipnx
              {\vbox to \vsize
                 {\hsize\!!widtha
                  \dorecurse\@@ipny
                    {\@@iptop
                     \hbox to \hsize
                       {\@@ipleft
                        \vbox to \!!heighta
                          {\hsize\!!widtha
                           \vsize\!!heighta
                           \ifnum\combinedpagescounter>\@@ipstop\relax
                             \globallet\@@ipn\!!zerocount
                           \else\ifnum\combinedpagescounter>\@@ipn \else
                             \externalfigure[#1]
                               [\c!object=\v!no,
                                \c!page=\combinedpagescounter,
                                \c!factor=\v!max,
                                \c!background=\@@ipbackground,
                                \c!backgroundcolor=\@@ipbackgroundcolor,
                                \c!frame=\@@ipframe]%
                           \fi\fi}%
                        \@@ipright}
                     \doglobal\increment\combinedpagescounter
                     \@@ipbottom}
                  \vfil}%
               \hfil}
            \hfilneg}
         \vfilneg}
         \page
      \ifnum\combinedpagescounter>\@@ipn \exitloop\fi}}

\protect