A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Ronald van Riet
Date: 2017 Dec 12, 01:18 -0800
this seems a fairly standard configuratin for what is usually called LOG-LOG rules or "electric" rules. The LL scales are used for calculations with all sorts of exponents (as are often used in electrical or electronical calculations, hence the name). European rules often have a P scale for higher precision of sin at angles near 90 degrees, but this doesn't seem to be common in the USA.
They are really very common and you should have no problem finding instructions for use or full user manuals on the internet.