The data managed by XPRafts is permanently stored on disk in a "database" file, an ordinary operating system file. This file should normally have a “.XP” extension.

The database stores both the graphical and non-graphical attributes of all objects in the network, as well as the non-specific or general control data associated with a network, such as job title and time steps for the solution procedure, mode of analysis, links to external interface files etc.