We can save this analysis as a chart file, with a .qdc file extension by selecting the Save button 
from the Chart window. This is particularly useful in this last example, since we used the Range and Query statements in the Chart Options dialog box to filter the data. Saving the chart will allow us to easily return to this point in the analysis, since the settings in the Chart Options dialog box are saved with the chart file (but not saved with the data file).
In contrast, you may choose whether options defined in the Analysis Options and Chart Format Options dialog boxes are applied to the data file, chart file or both.
· When these dialogs are opened from the chart file, you may select the Update Data Set option to save the changes with the data file. Otherwise, these changes are only saved with the chart file (if the chart file is saved).
· When these dialogs are opened from the data file, the changes are saved with the data file (if the data file is saved). Chart files are not automatically updated, but can be updated when they are opened, at your option.