Glossary:Ordinal number

ordinal number - number assigned to each element indicating the designed ordinal position of the element in the collection. Some collections are sorted by their ordinal numbers and this is the order in which they should usually be learned. Ordinal number comes with a collection, while the priority is set for each element by the user using his or her own criteria. By default, ordinal number is set to the number of elements in the current collection. This way, the first element you add will have the ordinal two (the root of the knowledge tree gets the ordinal one), second element will get three, etc. Ordinal numbers are useful in sorting the collection or its subsets