Genome Analysis, IMB Jena. Optionally, you may mask the query sequence for low-complexity regions. The statistical significance threshold for reporting matches against database sequences. If the statistical significance ascribed to a match is higher than the expect threshold, the match will not be reported. Lower expect thresholds are more stringent, leading to fewer chance matches being reported.
Fractional values are acceptable.
Beside that, the threshold value is restricted to a maximum of 5.0e-4. Literature Altschul, Stephen F., Warren Gish, Webb Miller, Eugene W. Myers, and David J. Lipman. Basic local alignment search tool. Methods for assessing the statistical significance of molecular sequence features by using general scoring schemes.