PDF4QT consists of a PDF rendering library and several applications,
such as an advanced document viewer, an editor, a diff viewer, a CLI,
and a document page manipulator application.
It implements the PDF reference 2.0.

features:
- color management
- optional content handling
- text layout analysis
- signature validation
- annotations
- form filling
- text to speech capability
- edition
- command line tool
- audio book conversion
- internal structure inspector
- compare documents
- static XFA support (readonly, simple XFA only)
- electronically/digitally sign documents
- public key security encryption
