Continuous archiving and wal generation

Hello list

I have a question concerning the continuous archiving process. The manual
says:

To make use of the backup, you will need to keep around all the WAL segment
files generated during and after the file system backup. To aid you in doing
this, the pg_stop_backup function creates a *backup history file* that is
immediately stored into the WAL archive area. This file is named after the
first WAL segment file that you need to have to make use of the backup. For
example, if the starting WAL file is 0000000100001234000055CD the backup
history file will be named something like
0000000100001234000055CD.007C9330.backup.

My question is: if I have a large database which takes some time to backup
with tar, and during the interval between pg_start_backup() and
pg_stop_backup() more than one wal file gets generated, do I have to store
in addition to the base backup all wal files generated during the backup
interval or just the one specified by the .backup file?

I'm trying to figure out the minimum required to restore from a backup, and
my common sense says that I should archive all the wal files produced during
the backup since they contain information of the data file changes made
during the backup.

Regards

M