I am using set-input-method in emacs (with (set-input-method "portuguese-prefix") in my .emacs file). I write notes on Portuguese grammar in a file opened in the org-mode. The file has both English and Portuguese in it. I notice that some words are highlighted yellow or orange, but I don't see the logic. If it is because some Portuguese word is interpreted as a wrongly spelled English word, then I also see many other Portuguese words that don't change their colour. Could someone explain what is going on? Thanks.