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The root tag of the XML file is plugin. The general tag contains information about the plugin like the display name, the folder, description and so on. The UUID is used to identify your plugin. You can generate one based on the cpoyright copyright and foldername field here: http://www.contenido.org/deutsch/detechnik/cmstools/Homeuuid-generator/index-c-1972-3.html
Next up is the requirements tag, Here we can list what software has to be installed in order for this plugin to work. There are lots of things you can check for, but we only need to make sure that the CONTENIDO version is 4.9.0 or greater and that the PHP version is 5.3 or newer.
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