Then, GFTAXTR designates data sets that have been opened only once for output during the time period of the study as USAGE(BACKUP). Many of the USAGE(BACKUP) data sets are referenced on a single calendar day, but GFTAXTR separates them before the USAGE(SINGLE) data sets because the USAGE(BACKUP) data sets might migrate earlier, after 0 days, than USAGE(SINGLE) data sets.

USAGE(BACKUP) data sets are eligible to migrate to migration level 2 after 0 days on primary storage and 0 days on migration level 1, in other words, directly to migration level 2.