- A statistical significance threshold for reporting database sequence matches. E is interpreted as the upper bound on the expected frequency of chance occurrence of an HSP (or set of HSPs) within the context of the entire database search.
- The maximum number of database sequences for which one-line descriptions will be reported. (The default value for V is 500.)
- The maximum number of display of the high-scoring segment pairs (alignments). (The default value for B is 250.)
Default parameters are used for the others.