Ambiguity symbol

An ambiguity symbol is one of 11 symbols (the letters 'B', 'D', 'H', 'K', 'M', 'N', 'R', 'S', 'V', 'W', 'Y') that are used in IUPAC notation to represent uncertainty at a particular nucleotide position in a DNA string, in addition to the standard DNA alphabet {A, C, G, T}. Ambiguity symbols were created to encode single-nucleotide variations.

For example, the symbol 'D' could represent either 'A', 'G', or 'T'. See the table below for a complete description of ambiguity symbols.

IUPAC notation