On Thu, 5 Nov 2020 at 11:57, Henri Menke <henri@henrimenke.de> wrote:

> %D The default dimensions are quite old and will not change. The funny
> fractions
> %D were introduced when we went from fixed dimensions to relative ones.
> Since
> %D \CONTEXT\ is a dutch package, the dimensions are based on the metric
> system.
> The
> %D asymmetrical layout is kind of handy for short quick||and||dirty stapled
> %D documents.
>
>
> https://github.com/contextgarden/context-mirror/blob/343fdd99ef79884fca1f86b49c950e03939aeedf/tex/context/base/mkiv/page-lay.mkiv#L1373-L1377


So it's for backward compatibility then.
Thanks for the nice anecdote!