| Symbol |
Meaning |
Logic for symbol |
Symbol for the complementary sequence |
| A |
Adenine |
Adenine |
T |
| C |
Cytosine |
Cytosine |
G |
| G |
Guanine |
Guanine |
C |
| T |
Thymine |
Thymine |
A |
| R |
G or A |
Purine |
Y |
| Y |
T or C |
Pyrimidine |
R |
| M |
A or C |
Amino (base having) |
K |
| K |
G or T |
Keto (base having) |
M |
| S |
G or C |
Strong (nature of base pairing) |
S* |
| W |
A or T |
Weak (nature of base pairing) |
W* |
| H |
A or C or T |
Not G** |
D |
| B |
C or G or T |
Not A** |
V |
| V |
A or C or G |
Not U** |
B |
| D |
A or G or T |
Not C** |
H |
| N |
A or C or G or T |
Nucleotide |
N |
