I found that response you gave @Grzesiek2010 in this forum query : Multiple select, constraint, one answer then nothing else
It works for me, using it with : not(selected(.,'nsp')) or count-selected(.) = 1, in the attached form
test_flood.xlsx (6.4 KB)
However, I should admit that I don't really understand the logic of this type of code, such as if(${inonde_hab}=’oui_une’,count-selected(.)=1,true()))
Which language is it? Is there a documentation about this kind of code? Thank you in advance