Teradata has various types of explicit or implicit constraints to support object relationship and Teradata specific data validation constraints.
The type of table-level check constraint or partitioning constraint (formerly referred to as indexes).
C = Explicit table-level constraint check
P = Non-partitioned Primary Index
Q = Partitioning constraint
S = Hash-Ordered Secondary Index without ALL
K = Primary Key
U = Unique constraint
R = References constraint
V = Value-Ordered Secondary Index without ALL
H = Hash-Ordered Secondary Index with ALL
O = Value-Ordered Secondary with ALL