Documentation explains wrongly what files compression affects

Here <http://www.percona.com/doc/percona-xtrabackup/2.1/innobackupex/streaming_backups_innobackupex.html> it says:

"When compression is enabled, xtrabackup compresses all output data, including the transaction log file and meta data files, using the specified compression algorithm. The only currently supported algorithm is ‘quicklz’. The resulting files have the qpress archive format, i.e. every *.qp file produced by xtrabackup is essentially a one-file qpress archive and can be extracted and uncompressed"

Only Innodb tablespaces seem to be compressed (.ibd s and ibdata1), no metadata, no logs, no non-innodb files.

To reproduce:
// create a compressed backup:
# innobackupex --compress --stream=xbstream /tmp > /media/backups/backup.xbstream
[...]
# cd /media/backups
# xbstream -x < backup.xbstream -C .
# qpress -d xtrabackup_logfile .
qpress: Source file was not compressed with qpress
# qpress -d ibdata1.qp .
// <---- no error

# xtrabackup -v
xtrabackup version 2.1.5 for Percona Server 5.1.70 unknown-linux-gnu (x86_64) (revision id: 680)
# innobackupex --version .
InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona LLC and/or its affiliates 2009-2013. All Rights Reserved.