Why are filesystems mounted with the relatime option?

Issue

• Entries in /etc/fstab with defaults mount options are mounted with the relatime option.

[user@localhost ~]$ grep -w / /etc/fstab
/dev/mapper/vg_localhost-lv_root /                 ext4    defaults        1 1

[user@localhost ~]$ grep lv_root /proc/mounts
/dev/mapper/vg_localhost-lv_root / ext4 rw,seclabel,relatime,barrier=1,data=ordered 0 0

• The mount(8) man page does not mention relatime in the list of options for the defaults option.

[user@localhost ~]$ man 8 mount
MOUNT(8)                   Linux Programmer’s Manual                  MOUNT(8)
...
       defaults
              Use default options: rw, suid,  dev,  exec,  auto,  nouser,  and
              async.