| Nucleotide symbol | Full Name |
| A | Adenine |
| C | Cytosine |
| G | Guanine |
| T | Thymine |
| U | Uracil |
| R | Guanine / Adenine (purine) |
| Y | Cytosine / Thymine (pyrimidine) |
| K | Guanine / Thymine |
| M | Adenine / Cytosine |
| S | Guanine / Cytosine |
| W | Adenine / Thymine |
| B | Guanine / Thymine / Cytosine |
| D | Guanine / Adenine / Thymine |
| H | Adenine / Cytosine / Thymine |
| V | Guanine / Cytosine / Adenine |
| N | Adenine / Guanine / Cytosine / Thymine |