Percent Complete Update
This gives you the ability to take an activity and enter a percent complete value. The gantt bar for that activity would then be split at that percentage. The portion that is complete would be moved to before the report start date. The portion that is uncomplete would act as it's own gantt bar that precedences can be built to and from.
Instructions
On the Home tab, in the Activities group, click Percent Complete Update to display the following panel.
Read Values from File
Use this option to read in data from an ASCII or CSV file.