When is an extremely simple personal calendar program, aimed at the Unix
geek who wants something minimalistic. It can keep track of things you
need to do on particular dates. There are a lot of calendar and
"personal information manager" programs out there, so what reasons are
there to use When?

- It's a very short and simple program, so you can easily tinker with it
  yourself.
- It doesn't depend on any libraries, so it's easy to install. You
  should be able to install it on any system where Perl is available,
  even if you don't have privileges for installing libraries.
- Its file format is a simple text file, which you can edit in your
  favorite editor.