.XER File Extension
File TypePrimavera P6 Project File
What is a XER file?
Project planning file created by Primavera P6, a project planning application; saves the tasks, timeline, materials, and other resources required for the project; enables a project manager to plan and track progress.
Primavera P6 was developed by Oracle after they acquired Primavera Systems, the creators of Primavera P3 (a predecessor to P6). P3 projects use the .P3 extension and can be imported using P6 by selecting from the application menu.