Like structures, sequences help you define an element type. A sequence can encapsulate multiple other types of elements. A sequence is an ordered element, and its size can increase during the execution:

// "employee” as defined in previous section
typedef sequence <employee> AssignmentOrderSeq;
typedef sequence <employee, 4> QuartelyAssignmentOrderSeq;
typedef sequence <sequence <<employee>, 12> AnnualAssignmentOrderSeq;
typedef sequence <sequence <employee> > CompleteAssignmentOrderSeq;

Additionally, arrays, constants, operations, attributes, value types, abstract interfaces, and exceptions can be defined with IDL as well as with this syntax that looks like a pseudocode.