Intergrbs充满了古老的教条，用于在GlorIoUs Emacs编辑中折叠代码。其中包括folding.el，outline-minor-mode和fold-dwim.el。唉，我可怜的不明智的头脑不能写出必要的elisp配置。
它被称为在nxml模式中概述，它在nxml模式文档的第4部分。哪个开始…
4 Outlining
nXML mode allows you to display all or part of a buffer as an outline,in a similar way to Emacs’ outline mode. An outline in nXML mode is based on recognizing two kinds of element: sections and headings. There is one heading for every section and one section for every heading. A section contains its heading as or within its first child element. A section also contains its subordinate sections (its subsections). The text content of a section consists of anything in a section that is neither a subsection nor a heading.
