For example, Medical Sciences are a sibling of Computer Science . On the other hand, Sciences is the parent of all the siblings listed above. Further down the tree structure, there are children of Computer Science such as History of Computing, Foundations of Computer Science, Software, Programming, Internet , etc. At the very bottom of the structure there are leaves, i.e. children that do not have further children. Please note that the root, branches, children, leaves, etc. are all elements in SuperMemo.
Yellow icons indicate dismissed topics or items.
Those elements do not participate in repetitions. The plus sign to the left of the element indicates that the element has children. You can see the children when you click the plus sign. The minus sign to the left of the element indicates that the element with children can be collapsed. Us ing the contents window - you can use operations such as Add, Sibling, Insert or Delete to build the tree directly in the contents window .