English: This Final Degree Project (FDP) is a collaboration with a Free Software project: GNU PDF. The goal of the GNU PDF project is to develop and provide a free, high-quality, complete and portable set of libraries and programs to manage the PDF file format, and associated technologies. These libraries have a very important focus on conformance with PDF standards and specifications, which is not covered by any of the free software PDF libraries. Currently, the main activity in the GNU PDF project is the development of the GNU PDF Library. This library provides functions to read and write PDF documents conforming to standardized specifications. The main goal of this FDP is the development of modules for the GNU PDF Library. As described down below, the current status of the development aims at tasks involved in lexical, syntactic and semantic analysis of PDF files. These processes begin in the object layer of the library. Additionally, some other tasks on implementing basic features are still pending. These features belong to the base layer. This collaboration FDP makes contributions to both layers.