Frequently Asked Question:
Are Optional Content Groups and Layers the same thing?
Are Optional Content Groups and Layers the same thing?
Optional Content Groups and Layers are the same thing in the world of Adobe Acrobat and Adobe Reader, but they are not the same thing in the world of Quick PDF Library. In the PDF Specification the technical term Optional Content Group (OCG) is used, however, in Acrobat the more familiar and commonly used term Layer is used.
According to section 8.11.2.1 of the PDF Specification (PDF 32000-1:2008):
An optional content group is a dictionary representing a collection of graphics that can be made visible or invisible dynamically by users of conforming readers. The graphics belonging to such a group may reside anywhere in the document: they need not be consecutive in drawing order, nor even belong to the same content stream. In Adobe Acrobat 6 and above, OCGs can be viewed by opening the Layers panel.
New OCGs can be created using the NewOptionalContentGroup function in Quick PDF Library.