The main documentation of the Warning_Status Procedure contains additional explanation of this code listing.
function Warning_Status (S) result(Warning) ! Input variable. type(Status_type), intent(in) :: S ! Status to be checked. ! Output variable. type(logical) :: Warning ! Warning condition boolean. !~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ! Verify requirements. VERIFY(Valid_State(S),1) ! S is valid. ! Set warning boolean. Warning = status_flag(S%status)%severity == 'Warning' ! Verify guarantees. ! Warning should be what it was set to. VERIFY(Warning .eqv. (status_flag(S%status)%severity == 'Warning'),2) return end function Warning_Status