| DictIterator | DictIterator is used to traverse key/value pairs in a dictionary. |
| Doc | The Class Doc. |
| DocSnapshot | The class DocSnapshot. |
| NameTree | A NameTree is a common data structure in PDF. |
| NameTreeIterator | NameTreeIterator is used to traverse key/value pairs in a NameTree. |
| NumberTree | A NumberTree is a common data structure in PDF. |
| NumberTreeIterator | NumberTreeIterator is used to traverse key/value pairs in a NumberTree. |
| Obj | Obj is a concrete class for all SDF/Cos objects. |
| ObjSet | ObjSet is a lightweight container that can hold a collection of SDF objects. |
| PDFTronCustomSecurityHandler | This class represents PDFTron Custom Security handler that applies PDFTron's custom encryption method on save. |
| ResultSnapshot | The class ResultSnapshot. |
| SDFDoc | SDFDoc is a low-level document representing a graph of SDF.Obj nodes that can be used to build higher-level document models such as PDF (Portable Document Format) or FDF (Forms Document Format). |
| SecurityHandler | Standard Security Handler is a built-in password-based security handler. |
| SignatureHandler | A base class for SignatureHandler. |
| UndoManager | The class UndoManager. |