system requires <a href=
  "http://www.gnu.org/software/make/make.html">GNU make</a>. At the Met Office
  we are currently using version 3.79.x and 3.80.</p>

  <p>Optionally, the build system can use <a href=
  "http://www.ifremer.fr/ditigo/molagnon/fortran90/">f90aib</a> to generate
  interface files. However, there is also a built in Perl based interface file
  generator which is quicker and better in most cases so you are unlikely to
  need f90aib unless you hit a problem with some particular code.</p>
