Search results are displayed in the following order.

  1. Precedence table of sequences with high homology scores
  2. Homologous sequences and their alignment
  3. Parameters and statistics

Note that the symbol “|” in the BLAST search results for nucleotide sequences indicates agreement between nucleotide sequences.
For amino-acid sequences, matching amino acids will be displayed.
The symbol “+” is used to indicate similarities between amino acids.

For further details, refer the original papers on BLAST.
BLAST Reference