A = Adenosine

S = G or C

C = Cytidine

W = A or T

G = Guanosine

Y = C or T

T = Thymidine

B = C, G or T

U = Uracil

D = A, G or T

K = G or T

H = A, C or T

M = A or C

V = A, C or G

R = A or G

N = any base