OmniOutliner makes use of MultiMarkDown.
MultiMarkdown Copyright (c) 2010-2015 Fletcher T. Penney MultiMarkdown is released under both the GPL and MIT licenses. You may pick the license that best fits your needs. Modifications to remove reliance on Glib2: Copyright (c) 2011 Daniel Jalkut, licensed explicitly MIT. LyX export code (c) 2013-2014 Charles R. Cowan, licensed under both GPL and MIT licenses. Portions based on: peg-markdown Copyright (c) 2008-2011 John MacFarlane ODF output code (c) 2011-2013 Fletcher T. Penney peg-markdown is released under both the GPL and MIT licenses. You may pick the license that best fits your needs. Original Markdown specification by John Gruber http://daringfireball.net/projects/markdown/ The MIT License Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. For more information, visit http://fletcherpenney.net/multimarkdown/