The figure shows the theoretical spectrum for a cross-linked pair of +1 peptides, kviknvaevk and lymead, linked at positions 4 and 6, respectively. As in SEQUEST, b- and y-ions are arbitrarily assigned a height of 50, with flanking peaks of height 25 and neutral losses (ammonia, water and carbon monoxide) of height 10. The peaks corresponding to the fragmentation illustrated on the left are colored as shown.