### How to break the 9-argument limit

If you think about it, you will realise that Knuth's command definition syntax:

      \def\blah#1#2 ... #9{<macro body>}

is intrinsically limited to just 9 arguments. There's no direct way round this: how would you express a 10th argument? - and ensure that the syntax didn't gobble some other valid usage?

If you really must have more than 9 arguments, the way to go is:

      \def\blah#1#2 ... #9{%
        \def\ArgI{{#1}}%
        \def\ArgII{{#2}}%
        ...
        \def\ArgIX{{#9}}%
        \BlahRelay
      }
      \def\BlahRelay#1#2#3{%
        % arguments 1-9 are now in
        %   \ArgI-\ArgIX
        % arguments 10-12 are in
        %   #1-#3
        <macro body>%
      }

This technique is easily extendible by concert pianists of the TeX keyboard, but is really hard to recommend.

LaTeX users have the small convenience of merely giving a number of arguments in the `\newcommand` that defines each part of the relaying mechanism: Knuth's restriction applies to `\newcommand` just as it does to `\def`. However, LaTeX users also have the way out of such barbarous command syntax: the keyval package. With keyval, and a bit of programming, one can write really quite sophisticated commands, whose invocation might look like:

      \flowerinstance{species=Primula veris,
        family=Primulaceae,
        location=Coldham's Common,
        locationtype=Common grazing land,
        date=1995/04/24,
        numplants=50,
        soiltype=alkaline
      }

The merit of such verbosity is that it is self-explanatory: the typist doesn't have to remember that argument twelve is `soiltype`, and so on: the commands may be copied from field notes quickly and accurately.

`keyval.sty`
  Distributed as part of macros/latex/required/graphics.tar.gz