Format specifiers allow backup file names to be customized.

The following substitiion variables can be used:

%a	Database Activition ID
%b	Base name – only vaied for SET NEWNAME and image copies
%c	Backup piece copy number
%d	Database name
%D	Day of month (DD)
%e	Archive log sequence number
%f	Absolute file number
%F	System-generated name. See below
%h	Archived redo log thread number
%I	DBID
%M	Month (MM)
%N	Tablespace name
%n	Database name – Right padded with ‘x’ character e.g. TESTxxxx
%p	Piece number within backup set
%s	Backup set number
%t	Backup set timestamp. Use with %s to provide unique name
%T	Date (YYYYMMDD)
%u	Short system generated file name.
%U	Long System generated file name.
%Y	Year (YYYY)
%%	Percent (%) character

RMAN Format Specifiers