Formats for digital preservation: A review of alternatives and issues

CENDI's mission is to help improve the productivity of federal science-and technology-based programs through the development and management of effective scientific and technical information support systems. In fulfilling its mission, CENDI member agencies play an important role in helping to strengthen U.S. competitiveness and address science-and technology-based national priorities. CENDI Members recognize digital formats as acceptable means of preserving Government information (CENDI, 2007). This review of alternative formats and the issues related to them was undertaken in the interest of implementing best practices in information life-cycle management, to dispel any misunderstandings related to digital formats, and to provide agencies with enough information so they can determine what the most appropriate preservation format is for them. BACKGROUND CENDI Members' interest in digital preservation formats was spurred on by the Office of Management and Budget's (OMB) call for government information management standards, the Chief Information Officers (CIO) Council's response to the E-government Act, the identification of archival formats for the digital deposit or records, and the development of agency repositories. In 2005 the CENDI Members requested an assessment of the digital formats being used for preservation and the issues surrounding them. The CENDI Digital Preservation Task Group submitted their final report on December 22, 2006. Many digital file formats can be considered for preservation. CENDI agencies, however, are most concerned with formats that best preserve text documents such as technical reports and journal articles. For this reason the report focuses on four major formats in the context of document preservation – TIFF, PDF, PDF/A, and XML. The appropriateness of TIFF, PDF, PDF/A, and XML formats was assessed by the Library of Congress as part of a more comprehensive evaluation using the following: ¾ Technical Factors, each format is analyzed against the following factors for sustainability: ƒ Disclosure – existence of complete documentation ƒ Adoption – degree to which the format is already in use ƒ Transparency – degree to which the digital representation is open to direct analysis ƒ Self-documentation – digital objects that contain basic descriptive, technical, and other administrative metadata ƒ External Dependencies – degree to which the format is dependent upon specific hardware, operating system, or software for rendering or use and the complexity of dealing with those dependencies in future technical environments ƒ Impact of Patents – degree to which the ability of archival institutions to sustain content in a format will be inhibited by patents ƒ Technical …