Represents the "VOffset" entry of the richmediaposition dictionary object.

It is an optional entry defined as part of the PDF 1.7 Extension Level 3 specification.

It contains a double representing a PDF numeric object.

It should have a positive value.

The PDF specification states that this item assumes a value of 18 if no value has been provided.

For definitive details see:.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 9.50f, page 85.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 340, page 703.