Sequences such as vectors or E. coli which are compared against readings using vector_clip (see section Vector_clip) and screen_seq (see section Screening for known possible contaminant sequences, usually via pregap4 (see section Pregap4), must be stored as plain text. i.e. the files should contain only the sequence data (no header or title) on records (lines) of up to 60 characters. Each record should be terminated by a newline character. No other characters should appear in the file.