IML Studio's graphics support two types of linked selection.
Global selection mode is the traditional linked-selection technique used in SAS/Insight and other products. In global selection mode, all data views (that is, plots or data tables) share a common selection state for observations. When you select an observation in one view, that observation is treated as selected in all other views.
Global selection mode enables you to graphically subset data by interacting with a single data view. For example, if you have three plots called A, B, and C, selecting observations in plot A causes plots B and C to display those same observations as selected.
In contrast, local selection mode enables you to subset data by interacting with multiple data views. Local selection mode was developed at SAS Institute. SAS/IML Workshop 2.0 was the first product to implement local selection mode.
In local selection mode, you specify each data view to be either a selector or an observer. You configure an observer to display either the union or the intersection of the selected observations in all selector views. For example, if you have three plots called A, B, and C, you can configure plot C to be the "observer of the intersection" of the other plots. This means that an observation is selected in plot C only if it is selected in both plot A and plot B.
You can manually select observations in selector views. You cannot manually select observations in an observer view. An observer view displays an observation as selected based on the observation's selection state in the selector views. An "observer of the union" (the union scheme) displays an observation as selected if the observation is selected in any of the selector views. An "observer of the intersection" (the intersection scheme) displays an observation as selected if the observation is selected in all of the selector views.
For further information concerning local selection mode, please refer to the following topics: