To keep data points that belong to different curves or symbol sets, you can make multiple data sets.
Change the name of the current data set by clicking on the leftmost button under the data set list in the top right of the window, or by choosing Rename data set from the Data menu.
Select the current data set by clicking on its name in the data set list in the top right of the window. The data points of the current data set will be indicated with markers. Selected data points will appear in another color than unselected data points.
You can create a new data set by clicking on the middle button under the data set list in the top right of the window, or by choosing New data set from the Data menu. You can delete the current data set and all its data points by clicking on the right button under the data set list in the top right of the window, or by choosing Delete data set from the Data menu.
You can duplicate an existing data set by choosing Duplicate data set from the Data menu. You can move selected points from an existing data set to another data set by choosing Move data to set from the Data menu, or by pressing Ctrl+M.
You can review all your data points in all your data sets by choosing Show all data as text from the Data menu, or by pressing Ctrl+W.
See also: Manipulating data.