'units' was new to me too. The version I have on my Mac wouldn't accept 'millilightseconds' but it would take 'milli-c-seconds' - presumably the units.lib datab

'units' was new to me too. The version I have on my Mac wouldn't accept 'millilightseconds' but it would take 'milli-c-seconds' - presumably the units.lib database is a little different from one in the original article.