The Links Modification Table Editor. Options for cleavage (Xase), modifications, and crosslinkers used in MS3D are defined using this interface. Some commonly used proteases, nucleases, crosslinkers and modifications arising from typical reactions are included and can be selected using the drop-down menus. Using the editor interface, users can add custom modifications (user-defined). Links analyses are highly flexible and exhaustive as multiple configurations can be defined and interrogated in a single run.