Although PDF is commonly understood as a single holistic file format, in reality, PDF comprises a number of distinct dialects, each designed to support a specific aspect of the format.
The PDF Association’s PDF cheat sheets are designed to help developers work more efficiently. They are highly condensed summaries, with information grouped to help inform on nuances or details that are often forgotten.
PDF Association members now have a new resource: advance previews of targeted test cases highlighting differences between implementations, including in-depth technical explanations.