$ LANG=fi_FI.UTF-8 locale -k -c LC_MESSAGES LC_MESSAGES yesexpr="^[KkJjYy].*" In addition to “k” for “kyllä” and “j” for “joo”, “o” for “on” should also be added for the affirmative response. ‘O’ is for ‘on’, which means ‘[it] is’ (or similar in other grammatical person, as appropriate), and is how one responds to ‘Onko ...’ (‘Is it ...’), as an alternative to ‘joo’ or ‘kyllä’ (‘yes’). Colloquially, people say ‘oo’ rather than ‘on’, so the letter ‘o’ (in addition to ‘j’ and ‘k’) is appropriate.
Gosh, bugzilla, it's 2009, learn some Unicode. Let's try this again: In addition to 'k' for 'kyllä' and 'j' for 'joo', 'o' for 'on' should also be added for the affirmative response. 'O' is for 'on', which means '[it] is' (or similar in other grammatical person, as appropriate), and is how one responds to 'Onko ...' ('Is it ...'), as an alternative to 'joo' or 'kyllä' ('yes'). Colloquially, people say 'oo' rather than 'on', so the letter 'o' (in addition to 'j' and 'k') is appropriate.
I think this would be an unnecessary addition. Grammatically both answers are correct for your example question but 'kyllä' sounds perhaps slightly more formal. It should be also noted that CLDR includes only 'kyllä'/'ei' and no 'joo' or 'on'. > Colloquially, people say 'oo' rather than 'on' I haven't yet met such people even I'm a Finn :)
Going with comment #2 I won't change anything. It is also dangerous to accept too many variants. If any accidental keypress can be interpreted as a result you better not have cats running across your keyboards.