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 2 (the root of the knowledge tree gets the ordinal 1), second element will get 3, etc. Ordinal numbers are useful in sorting the collection or its subsets

The root in a newly crated collection has ordinal 0, whereas the first element added and all those following get ordinal 100. Either is SM behaving 
weird, or this explanation needs review