例如；backup incremental level 0 database format='lev0_%d_%t_%u_%s_%p'
format=string文件路径和名称的格式串，其中的含义是：
%c copy ID
%p backup piece ID
%s backup set ID
%e log Sequence
%h log thread ID
%d database name
%n database name(x填充到8个字符)
%I DBID
%f file ID
%F DBID , day ,month ,year and sequence的复合格式
%N tablespace name
%t timestamp
%M mh mm格式
%Y year yyyy格式
%u backup set+time(x填充到8个字符))
%U %u_%p_%c
%% %
The format specifier %U is replaced with unique filenames for the files when you take backups.
the %F element of the format string combines the DBID, day, month, year, and sequence number to generate a unique filename. %F must be included in any control file autobackup format.

上边不是有说明吗？