> You should use Letter or A4 as appropriate for your relationship with the metric system. That's pretty clearly stated near the top of the article. As a Europ

> You should use Letter or A4 as appropriate for your relationship with the metric system. That's pretty clearly stated near the top of the article. As a European, if I wrote a similar post I would do it all in metric and trust that my US readers were smart enough to substitute the units of their choice without whining about it. The concepts would not change, and a quick google would tell you that an inch is approx 25mm, which is enough for you to understand what's going on.