Represents the "Phoneme" 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 string object.

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.

The Phoneme entry holds the phonetic transcription of this element content using the alphabet named by PhoneticAlphabet. Text-to-speech engines use this when standard rules would give an incorrect pronunciation.