ProtectData Property [Excel 2003 VBA Language Reference]
True if series formulas cannot be modified by the user. Read/write Boolean.
This property is not persisted when the file is saved. If you set this property to True and then reopen the file, it will no longer be set to True.
This example protects the data on embedded chart one on worksheet one.
Worksheets(1).ChartObjects(1).Chart.ProtectData = True
Applies to | Chart Object