rman backup command syntax error

This is my first try at an RMAN backup.
 
I have run configure commands to configure the channels.
 
When I issue the following backup command it gives an error.  What am I doing 
wrong?
 
Contents of the rman_backup.txt file are:
 
backup database as compressed plus archivelog delete input;
 
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-00558: error encountered while parsing input commands
RMAN-01009: syntax error: found "as": expecting one of: "archivelog, backup, bac
kupset, channel, copy, controlfilecopy, current, database, datafile, datafilecop
y, delete, diskratio, db_recovery_file_dest, filesperset, format, from, force, i
nclude, keep, (, maxsetsize, noexclude, nokeep, not, pool, plus, reuse, recovery
, ;, skip, spfile, setsize, tablespace, tag, to"
RMAN-01007: at line 1 column 17 file: f:\dba\bin\rman_backup.txt
 
RMAN>
 
 
Jeffrey Beckstrom
Database Administrator
Greater Cleveland Regional Transit Authority
1240 W. 6th Street
Cleveland, Ohio 44113

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