Represents the "PhoneticAlphabet" entry of the structure element dictionary object.

It is an optional entry defined as part of the PDF 2.0 specification.

It contains a string representing a PDF name object.

The PDF specification states that this item assumes a value of "ipa" if no value has been provided.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 323, page 558.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 355, page 723.