Schedule Mechanics & Data
XER File
An .xer file is Primavera P6's plain-text, tab-delimited export format -- a stack of separate tables (activities, relationships, calendars, and more) rather than a single flat file.
Definition
A .xer export is structured as a series of tables, each starting with a %T line naming the table, a %F line listing its column names, and one %R line per data row. TASK holds activities, TASKPRED holds relationships, PROJWBS holds the Work Breakdown Structure, and CALENDAR holds work calendars, among dozens of other tables covering resources, activity codes, and administrative settings. Despite the similar-looking extension, it is not XML -- it's closer to several CSV files concatenated together with headers marking where each one starts.
Example
Opening a .xer file in a text editor shows readable rows like "%T\tTASK" followed by a %F header row and dozens of %R data rows -- one per activity in the project.