Contents of "backup_label" and "*.backup" in pg_wal location

Hello Hackers,

I have a question regarding the contents being written to the backup_label
file and the .backup file in the pg_wal location generated when the online
backup is done.

backup_label file contents are as follows, which do not contain backup stop
position (timestamp and STOP WAL location). The below information is
written when pg_start_backup() is done.

START WAL LOCATION: 0/44000060 (file 000000010000000000000044)
CHECKPOINT LOCATION: 0/44000098
BACKUP METHOD: pg_start_backup
BACKUP FROM: master
START TIME: 2016-11-04 14:24:25 AEDT
LABEL: 222

I see the following contents in the file
"000000010000000000000044.00000060.backup" which was generated in the
pg_wal location during the online backup. When pg_stop_backup() is
executed, the following content is written which includes the content
copied from the backup_label file.

START WAL LOCATION: 0/44000060 (file 000000010000000000000044)
STOP WAL LOCATION: 0/44000168 (file 000000010000000000000044)
CHECKPOINT LOCATION: 0/44000098
BACKUP METHOD: pg_start_backup
BACKUP FROM: master
START TIME: 2016-11-04 14:24:25 AEDT
LABEL: 222
STOP TIME: 2016-11-04 14:25:09 AEDT

Can someone please help me know the importance of the above file ?
How about having the same contents in the backup_label file as well ?

I am working on another patch and was thinking it would be good if the same
contents can be written to backup_label file as well. Actually, it would be
more beneficial to do so.

As of now, the backup_label file does not have any information related to
when and at what position the backup actually completed.

Any thoughts / apprehensions ?

Regards,

Venkata B N
Database Consultant

Fujitsu Australia