# RMAN Format Codes **Restrictions and Usage Notes** Any name that is legal as a sequential filename on the platform is allowed, so long as each backup piece or copy has a unique name. If backing up to disk, then any legal disk filename is allowed, provided it is unique. **Keywords and Parameters**
Syntax Element Description
%aSpecifies the activation ID of the database
%cSpecifies the copy number of the backup piece within a set of duplexed backup pieces. If you did not duplex a backup, then this variable is 1 for backup sets and 0 for proxy copies. If one of these commands is enabled, then the variable shows the copy number. The maximum value for %c is 256.
%dSpecifies the name of the database
%DSpecifies the current day of the month from the Gregorian calender in format DD
%eSpecifies the archived log sequence number
%fSpecifies the absolute file number
%FCombines the DBID, day, month, year, and sequence into a unique and repeatable generated name. This variable translates into **c-IIIIIIIIII-YYYYMMDD-QQ**, where **IIIIIIIIII** stands for the DBID. The DBID is printed in decimal so that it can be easily associated with the target database. **YYYYMMDD** is a time stamp in the Gregorian calendar of the day the backup is generated and **QQ** is the sequence in hexadecimal number that starts with 00 and has a maximum of FF (256)
%hSpecifies the archived redo log thread number
%ISpecifies the DBID
%MSpecifies the month in the Gregorian calendar in format MM
%NSpecifies the tablespace name
%nSpecifies the name of the database, padded on the right with x characters to a total length of eight characters. For example, if the prod1 is the database name, then the padded name is prod1xxx.
%pSpecifies the piece number within the backup set. This value starts at 1 for each backup set and is incremented by 1 as each backup piece is created. If you specify PROXY, then the %p variable must be included in the FORMAT string either explicitly or implicitly within %U
%sSpecifies the backup set number. This number is a counter in the control file that is incremented for each backup set. The counter value starts at 1 and is unique for the lifetime of the control file. If you restore a backup control file, then duplicate values can result. Also, CREATE CONTROLFILE initializes the counter back to 1
%tSpecifies the backup set time stamp, which is a 4-byte value derived as the number of seconds elapsed since a fixed reference time. The combination of %s and %t can be used to form a unique name for the backup set
%TSpecifies the year, month and day in the Gregorian calendar in this format: <tt>YYYYMMDD</tt>
%uSpecifies an 8-character name constituted by compressed representations of the backup set or image copy number and the time the backup set or image copy war created
%USpecifies a system-generated unique filename (default). The meaning of %U is different vor image copies and backup pieces. For a backup piece %U specifies a conveniant shorthand for %u\_%p\_%c that guarantees uniqueness in generated backup filenames. If you do not specify a format when making a backup, then RMAN uses %U by default. For an image copy of a datafile %U means **data-D-%d\_id-%I\_TS-%N\_FNO-%f\_%u**. For an image copy of an archived redo log %U means **arch-D\_%d-id-%I\_S-%e\_T-%h\_A-%a\_%u**. For an image copy of a control file %U means **cf-D\_%d-id-%I\_%u**
%YSpecifies the year in the format **YYYY**
% %Specifies the '%' character. For example, %%Y translates to the string %Y