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，其中可包含宏变量：
| 符号 | 含义 |
|---|---|
| %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 sequencer的复合 |
| %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.