DocOnce is two things: . 1. DocOnce is a very simple and minimally tagged markup language that looks like ordinary ASCII text (much like what you would use in an email), but the text can be transformed to numerous other formats, including HTML, Wiki, LaTeX, PDF, reStructuredText (reST), Sphinx, Epytext, and also plain text (where non-obvious formatting/tags are removed for clear reading in, e.g., emails). From reStructuredText you can go to XML, HTML, LaTeX, PDF, OpenOffice, and from the latter to RTF and MS Word. From Pandoc one can generate Markdown, reST, LaTeX, HTML, PDF, DocBook XML, OpenOffice, GNU Texinfo, MediaWiki, RTF, Groff, and other formats. . 2. DocOnce is a working strategy for never duplicating information. Text is written in a single place and then transformed to a number of different destinations of diverse type (software source code, manuals, tutorials, books, wikis, memos, emails, etc.). The DocOnce markup language support this working strategy. The slogan is: "Write once, include anywhere".