You save a selection of loop devices in a graphic to perform actions on all of them later, at the same time. The selection is only available in the graphic where you save it.
In WorkStation or WebStation, in a graphic, click a loop device. On the Actions menu, click the multiselect icon
Click the Save icon.
In the pop-up, write a name for your selection. If you write a name that is used in a saved selection, you will be asked if you want to replace that selection with the new one.
Click OK to save the selection, click Cancel to cancel.
The selection is saved or not saved, depending on your choice.