For settings under Basic, All Walk, and Search Settings, a user must
have read access to the profile as well as read access to the specific
setting in order to see the setting. Write access to the profile, and
write and delete access to the setting, is needed in order to modify a
setting. (Delete is needed to clear a setting, which may not be
apparent from the form.) Note that some settings are grouped on a
line, such as the Robots setting: permissions can be granted
to the group as a whole (Robots), or only specific settings
in the group (Robots - robots.txt or Robots - Meta).
If a user has no read access to a setting, it will not be displayed on
the page. If a user has no write access to a setting, it will be
disabled (grayed out and not modifiable).