Home Software Services About Contact usearch manual
-output_no_hits option
Specifies that a record should be written to search or clustering output files if there are no hits for the query sequence. By default, no records are written except for uc files, which always have N (no-hit) records for unmatched queries.

A star (*) is written in place of the target label. Placeholders (zeroes or empty values) are written in other fields of the record.