This package contains the tools x2sys_datalist, which allows you to extract data from almost any binary or ASCII data file, and x2sys_cross which determines crossover locations and errors generated by one or several geospatial tracks. Newly added are the tools x2sys_init, x2sys_binlist, x2sys_put, and x2sys_get which extends the track-management system employed by the mgg supplement to generic track data of any format. This package represents a new generation of tools intended to replace the old ``X_SYSTEM'' crossover tools (below). The package is maintained by Paul Wessel.