These levels exist since the DSM-5, which is not yet in use everywhere: The DSM-5 introduced three ASD levels of severity: level 1 (“requiring support”), level

These levels exist since the DSM-5, which is not yet in use everywhere: The DSM-5 introduced three ASD levels of severity: level 1 (“requiring support”), level 2 (“requiring substantial support”), and level 3 (“requiring very substantial support”). https://www.autismspeaks.org/levels-of-autism https://www.autismspeaks.org/levels-of-autism has a good complete overview.