A collection is simply a group of items which is usually a List#1.3.6.1.4.1.33097.1.0.0 or Set#1.3.6.1.4.1.33097.1.0.6. However, most data structures are groups of things so it is likely that any data structure in this corpus is a collection. Graphs#1.3.6.1.4.1.33097.1.0.14 and Maps#1.3.6.1.4.1.33097.1.0.3 are considered collections.