This property represents the "Nums" entry of the number tree
node dictionary object.
It is defined as part of the PDF 1.0 specification.
An Array containing alternate keys and values. For this reason
the number of items in they array is always a multiple of two.
So to find the 10th key and value you would use a zero based
index of 20 and 21 respectively.
The pairs in this array should be sorted in ascending order by
For definitive details see:.
The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 37,