reStructuredText format [1] is another plaintext markup format similar to Markdown, in use initially only for Python documentation, but since some years also for other documentation, like for the Linux kernel or CMake. The KDE community uses files of that format currently at least for ECM documentation and hig.kde.org. While there is no own logo known (to me) for the reStructuredText format, it is currently strongly coupled to the tool Sphinx [2], so for a start using the logo of Sphinx in the text-x-rst icon as identifying item might be a solution. The next version of shared-mime-info will contain support for the MIME type, using the id string "text/x-rst" [3]. [1] https://en.wikipedia.org/wiki/ReStructuredText [2] http://www.sphinx-doc.org [3] https://cgit.freedesktop.org/xdg/shared-mime-info/commit/?id=02597c16914155cd16b22992ad57f49825bd835e