Working with collection types v17

A collection is a set of ordered data items with the same data type. Generally, the data item is a scalar field. It can also be a user-defined type such as a record type or an object type. In this case, the structure and the data types that make up each field of the user-defined type must be the same for each element in the set. Reference each data item in the set by using subscript notation inside a pair of parentheses.