Some attributes and element values in crosslinking.xml are restrictions of the string-type and can accept one of the fixed values defined in a special enumeration-list.
Strategy used when identifying peptides or pairs of peptides with crosslinks
List of values
| Value | Description |
| None | No crosslinking |
| Brute-force | Find intact crosslinks among all pairs of peptides |
| CID-ETD-MS2 | Attempt to match CID and ETD scans using pairs of candidate peptides |
| CID-MS2-MS3-hybrid | Attempt to match MS2 scans using pairs of candidate peptides and MS3 scans using individual candidate peptides |
| CID-MS3 | Attempt to match MS3 scans using individual candidate peptides |