| Code | Meaning | Equivalence | Complement |
|---|---|---|---|
| A | Adenine | A | T or U |
| C | Cytosine | C | G |
| G | Guanine | G | C |
| T or U | Thymine Uracil |
T or U | A |
| M | Amino | A or C | K |
| R | Purine | A or G | Y |
| W | Weak (2 bonds) | A or T | W |
| S | Strong (3 bonds) | C or G | S |
| Y | Pyramidine | C or T | R |
| K | Keto | G or T | M |
| V | Not T or U | A or C or G | B |
| H | Not G | A or C or T | D |
| D | Not C | A or G or T | H |
| B | Not A | C or G or T | V |
| N or X | Any | A or C or G or T | N or X |