Thank you to all who replied.
May I just repeat that I only want to know what the Automatic setting is (Automatic(xxxxxx) in Tools-Options-LibreOffice-View in the User Interface icon style list box.
This is only to verify the accuracy of the statement in the guide, irrespective of what we change to for our own use.
If that alters anyone's answer please feel feel free to respond.
Again, thank you for taking the time.
JohnS