single raw format; formats can be similar or radically different. Different manufacturers use their own proprietary and typically undocumented formats, which are collectively known as raw format. Often they also change the format from one camera model to the next. Several major camera manufacturers, including Nikon, Canon and Sony, encrypt portions of the file in an attempt to prevent third-party tools from accessing them. This industry-wide situation of inconsistent formatting has concerned many photographers who worry that their valuable raw photos may someday become inaccessible, as computer operating systems and software programs become obsolete and abandoned raw formats are dropped from new software. The availability of high-quality open source software which decodes raw image formats, particularly dcraw, has helped to alleviate these concerns. An essay by Michael Reichmann and Juergen Specht stated "here are two solutions – the adoption by the camera industry of A: Public documentation of RAW [sic] formats; past, present and future, or, more likely B: Adoption of a universal RAW [sic] format". "Planning for [US] Library of Congress Collections" identifies raw-file formats as "less desirable file formats", and identifies DNG as a suggested alternative. DNG is the only raw image format for which industry-wide buy-in is being sought. It is based upon, and compatible with, the ISO standard raw image format ISO 12234-2, TIFF/EP, and is being used by ISO in their revision of that standard. The ISO standard raw image format is ISO 12234-2, better known as TIFF/EP. (TIFF/EP also supports "non-raw", or "processed", images). TIFF/EP provided a basis for the raw image formats of a number of cameras. For example, Nikon's NEF raw files are based on TIFF/EP, and include a tag which identifies the version of TIFF/EP they are based on. Adobe's DNG raw file format was based on TIFF/EP, and the DNG specification states "DNG ... is compatible with the TIFF-EP standard". Several cameras use DNG as their raw image format, so in that limited sense they use TIFF/EP too. Adobe Systems launched this DNG raw image format in September 2004. By September 2006, several camera manufacturers had started to announce support for DNG in newer camera models, including Leica, Samsung, Ricoh, Pentax, Hasselblad (native camera support); and, Better Light (export). The Leica Digital-Modul-R (DMR) was first to use DNG as its native format. In September 2009 Adobe stated that there were no known intellectual property encumbrances or license requirements for DNG.