ME has since been removed. Initially, Kowalczyk did not release a 64-bit version of Sumatra, indicating that while it might offer slightly more speed and available memory, he believed at that time that it would greatly add to user confusion and that the benefits would not outweigh the potential costs. However, some users requested 64-bit builds of Sumatra and other developers had compiled unofficial 64-bit builds which loaded documents faster than the 32-bit builds. However, the official builds' developer had requested that unofficial builds not bear the 'Sumatra' name. In October 2015, an official 64-bit version of Sumatra was released. The Sumatra source code was originally hosted on Google Code. Due to US export legal restrictions, it was unavailable "in countries on the United States Office of Foreign Assets Control sanction list, including Cuba, Iran, North Korea, Sudan and Syria." The source code is currently hosted on GitHub. History The first version of Sumatra PDF, designated version 0.1, was based on Xpdf 0.2 and was released on 1 June 2006. It switched to Poppler from version 0.2. In version 0.4, it changed to MuPDF for more speed and better support for the Windows platform. Poppler remained as alternative engine for a time, and from version 0.6 to 0.8 it was automatically used to render pages that MuPDF failed to load. Poppler was removed in version 0.9, released on 10 August 2008. In July 2009, Sumatra PDF changed its license from GNU GPLv2 to GNU GPLv3 to match the same license change on MuPDF. Version 1.0 was released on 17 November 2009, after more than three years of cumulative development. Version 2.0 was released on 2 April 2012, over two years after the release of version 1.0. In 2007, the first unofficial translations were released by Lars Wohlfahrt before Sumatra PDF got official multi-language support. In October 2015, version 3.1 introduced a 64-bit version, in addition to their original 32-bit version. Name and artwork The author has indicated that the choice of the name "Sumatra" is not a tribute to the Sumatra island or coffee, stating that there is no particular reasoning behind the name. The graphics design of Sumatra is a tribute to the cover of the Watchmen graphic novel by Alan Moore and Dave Gibbons. Critical reception Sumatra has attracted acclaim for its speed and simplicity, for being portable, its keyboard shortcuts, and its open-source development. At one time