Represents the "Next" entry of the action dictionary object.
It is an optional entry defined as part of the PDF 1.2
It contains an array which contains ActionElements.
If you read the specification you will see that an array of one
ActionElement may be represented as a
single ActionElement rather than an
array. However we always present this property as an array to
simplify the interface. It is only if you add or remove items in
the array, that the underlying representation will be changed.
For definitive details see:.
The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 193,
The ISO PDF
Specification, ISO 32000-2:2017 PDF 2.0; Table: 196, page 503.