The Tool Buttons - Annotated Peptide Sequence
The peptide sequence button displays the peptide referred to in any selected result, along with the identified fragment ions.
The current version of MassAI supports up to three different peptide sequences per scan.
Having more than one peptide to a single precursor happens in cross-linking, where two peptides are chemically linked and
appear as one species. One peptide in a cross-link (the "A" peptide) generally fragments much more intensely than the other
(the "B" peptide). This often proposes a challenge to validation.  It is of great value however, when we observe b/y ions on
both sides of the cross-linked residue.

It is not unusual either to observe three peptides in a cross-link. In this case, one of the peptides (here referred to as peptide
"C" as in "center") has two reactive residues, which have both linked to another peptide.