oracle 定期备份并清理归档以及过期备份的脚本

我需要每周六做一个0备份，没天（除周六）做一个1备份，兵器备份以及归档只保留一个月，下面是我找的一个脚本，前面备份部分能理解，后面的删除部分 不太懂，谁能帮我解释下，或者有没有能实现我需求的脚本。

run {

allocate channel oem_backup_disk1 type disk format 'F:\\BACKUP\\FULL\\\\KHT\%U' maxpiecesize 80 G;

backup incremental level 0 cumulative as COMPRESSED BACKUPSET tag '%TAG' database include current controlfile;

sql 'alter system checkpoint';

sql 'alter system switch logfile';

sql 'alter system archive log current';

backup as COMPRESSED BACKUPSET tag '%TAG' archivelog all not backed up delete all input;

release channel oem_backup_disk1;

allocate channel t2  type disk ;

crosscheck backup;

crosscheck archivelog all;

delete noprompt archivelog until time 'sysdate-7';

delete noprompt archivelog all completed before 'sysdate-7';

delete expired archivelog all;

report obsolete;

delete noprompt obsolete recovery window of 60 days;

delete noprompt expired backup;

release channel t2;

}