S - Stretcher
G - Cove Base
ST - Two Faced Units
U - Bond Beam Unit (Round)
C - Cap or Sill
J - Jamb
V - Vertically Coursed Unit
X - Partially Glazed Face
CC - Capped Both Sides
P - Square Corner
O - Bullnose Corner
L - Left Handed Unit
R - Right Handed Unit

The first number in a shape code represents the block's thickness (bed depth). Please note the respective thicknesses available listed under each shape.