1. GFDL – The GNU Free Documentation License is a copyleft license for free documentation, designed by the Free Software Foundation for the GNU Project. , if produced in larger quantities, the original document or source code must be made available to the work's recipient. The GFDL was designed for manuals, textbooks, documentation which often accompanies GNU software. However, it can be used for any text-based work, regardless of matter. For example, the online encyclopedia Wikipedia uses the GFDL for all of its text. The GFDL was released in September 1999. After revisions, version 1.1 was issued in November 2008. The current state of the license is version 1.3. Material licensed under the current version of the license can be used for any purpose, long as the use meets certain conditions. All previous authors of the work must be attributed. All changes to the work must be logged. All derivative works must be licensed under the same license. Technical measures such as DRM obstruct distribution or editing of the document. The license explicitly separates any kind of "Document" from "Secondary Sections", which exist as front-matter materials or appendices. Not any subject matter itself.GFDL – The GFDL logo
2. Wiki markup – Its purpose is to be converted by wiki software into HTML, which, in turn, is served to web browsers. It was created on the original wiki site, WikiWikiWeb. There is commonly accepted standard language. Justification, keywords and so on depend on the particular wiki software used on the particular website. Different Wiki programs may support use of different sets of HTML elements within wikitext. In some cases, permitted HTML elements may be configured by individual wiki sites. MediaWiki supports many common HTML tags. There are different syntax conventions for these links. Many wikis, especially the earlier ones, used CamelCase to mark words that should be automatically linked. In MediaWiki, this convention was replaced with the notation, which Wikipedia calls "free links". Creole is an effort for a "common language to be used across different Wikis". There are several wiki engines that have implemented Creole. Version 1.0 of the specification was released in July 2007. It is not supported by MediaWiki. VisualEditor is an alternative to editing the raw wiki markup code.Wiki markup – Screenshot of the edit window in a Wikipedia article. Note the <nowiki> tag, used to escape wiki markup and HTML. HTML comments can be seen inside the <!-- --> tags.