CloneMe! beta
| Symbol | Nucleotide(s) | Description |
| A | A | Adenosine |
| C | C | Cytidine |
| G | G | Guanosine |
| T | T | Thymidine |
| R | = A or G | puRines |
| Y | = C or T | pYrimidines |
| W | = A or T | Weak hydrogen bonding |
| S | = G or C | Strong hydrogen bonding |
| M | = A or C | aMino group at common position |
| K | = G or T | Keto group at common position |
| H | = A, C or T | not G |
| B | = G, C or T | not A |
| V | = G, A, C | not T |
| D | = G, A or T | not C |
| N | = G, A, C or T | aNy |