E-value or Expect-value is the expected number of hits with at least this score. The lower the e-value the more significant the hit. The lower EXPECT thresholds are more stringent, leading to fewer chance matches being reported. Fractional values are acceptable. The default value is 10, such that 10 matches are expected to be found merely by chance, according to the stochastic model of Karlin and Altschul (1990).