Quick nitpick on Polish keyboard layouts. The "Polish (standard)" is more often referred to as the "typist" layout in Poland. IBM's docs say this is required for government contracts. I haven't seen it in any dev or home environments, but it wouldn't surprise me if some compliance-focused IT departments in the government enforce it.

<Note the duplicated entries for two of the diacritics that are used in Polish.> - did the author conflate ż with ź? A rookie mistake! :)

I'm running the 'pl' layout on my Linux box. The Alt(Gr) layer outputs the following: ≠²³¢€½§·«»–śðæŋ’ə…łźć„”ńµ≤≥. Some are expected (diacritics, €), but the presence of characters like ¢, ð, æ, ŋ, and ə is somewhat baffling, I wonder what's the history here.