Warhammer 40k - Lexicanum:Export pages
Export pages is a Special pages tool from the category Page tools. This tool produces an XML file containing the wikitext and metadata of either the current version only, or all revisions, of one or more pages, specified in the form of a list; the XML file is in the format required for the tool Import pages. Exporting is typically done either in preparation of applying the latter at another MediaWiki project, or for searching within old page revisions.
You can also simply click here.
In the tool you have to enter the Category of the articles you want to export. Or you can manually add individual articles.