AD7997/7998 ALERT/BUSY Pin

For the AD7997 / AD7998 If the ALERT/BUSY functionality is not being used can the ALERT/BUSY pin be left float or must it be tied high or low?  I see guidance here to tie the CONVST pin low if it will not be used but do not see anything specific to ALERT/BUSY.  Preference of course is leave it float.

thx - sean