What do these RMAN listings mean?
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Column  Indicates
Key
A unique key identifying this backup set.
If you are connected to a recovery catalog, then BS Key is the primary key of the backup set in the catalog. It corresponds to BS_KEY in the RC_BACKUP_SET view. If you are connected in NOCATALOG mode, then BS Key displays the RECID from V$BACKUP_SET.
TY
The type of backup: backup set (B) or proxy copy (P).
LV
The level of the backup: NULL for nonincrementals, level 0 or 1 for incrementals.
S
The status of the backup: A (available), U (unavailable), or X (all backup pieces in set expired). Refer to the CHANGE, CROSSCHECK, and DELETE commands for an explanation of each status.
Device Type
The type of device on which the backup was made, for example, DISK or sbt.
Completion Time
The date and time that the backup set completed. Note that the format of this field depends on the NLS_LANG and NLS_DATE_FORMAT environment settings.
Pieces
The number of backup pieces in the backup set.
Copies
The number of copies made of each backup piece in the set. The number is 1 if no duplexing was performed. Otherwise, the value ranges from 2 to 4.
Tag
The tag applied to the backup set; NULL if none. An asterisk (*) indicates multiple copies with different tags. Note that tag names are not case sensitive and display in all uppercase.
Reference --&gt; https://docs.oracle.com/cd/B13789_01/server.101/b10770/rcmsynta36.htm#83097
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