(We thank Dr. Westfall, ALPO,  for the Authorization)
 

The classification system itself is designed to describe the physical characteristics of a dome by means of a combination of letters and numbers. A brief outline of this system is

Broad Category
D----Dome
DC---Dome complex (several dome in physical contact e.g., Rumker)

Surroundings:
U---Uplands
W---Maria
UW-Uncertain if uplands or Maria.

Plan; Malor Axis is:
1.Less than 5 kilometers;
2.  5 to 20 kilometers
3.  20 t0 35 kilometers
4.  over 35 kilometers

( Always try to give a more exact size in your written notes)

Border:

a.  Circular (major:minor axes 1.00-1.25);
b.  elliptical (major:minor axes 1.26-2.00);
c.  Polygonal
d.  Irregular
e.  Too ill-defined to classify.

Profile-Average Slope

5.  Gentle (under 2)
6.  Moderate ( 2-5)

Profile-Cross Section
f.  Hemispherical
g.  Flat summit (platykurtic)
h.  sharp summit (leptokurtic)
i.  multiple summit ( more then one summit, but of single type)
j.  hemispherical-asymmetric
k.  flat summit-asymmetrical
l.  sharp summit asymmetric
m.  complex summit ( more than one summit and of different types)

surface detail-type
7.  depression(pit,craterlet, or saucer)
8.  elevation (hill, ridge, or peak)
9.  cleft or valley
10.  no observable detail

Surface detail-position
j.  central
k.  off-center
l.  on margin
m.  transversal (crosses dome)
n.  more than one such feature
 

An example of the system in use would be DW/2b/6f/7j9m8p. Translated this describes: A dome on a mare, 5 to 20 kilometers in diameter, elliptical in shape with an average slope angle between 2 and 5,  and hemispherical cross section. Its surface contains a central depression, a cleft that cuts across its margin, and several elevations.