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PSGML is an emacs major mode for SGML documents.PSGML has several functions for editing SGML documents. Indentationaccording to element nesting depth and identification of structuralerrors (but it is not a validating SGML parser). Menus and commandsfor inserting tags with only the contextually valid tags. Attributevalues can be edited in a separate window with information abouttypes and defaults. Structure based editing includes movement andkilling; and also several commands for folding editing.