XML is the replacement for CVS (comma separated variables) files and just about every other structured data file, except for long lists, which are better suited to relational databases.
Data with an internal relationship, think chapters of a book, can be stored in one XML file with the chapter divisions defined via XML. When the book becomes too big for XML, you can place each chapter in a separate file and relate the chapters through a separate XML file or using a relational database. You can also store the XML in a database instead of a files. Continuous audio and video files, think radio and television, use other formats for compatibility with old analogue formats. Forget all the weird file formats, if you do not need a database, use XML.
XMLSpy is an XML editor. I am looking at the XMLSpy version chart. I need part of the professional edition. The professional edition cost €399, about AU$499 or US$517. I am not about to spend $499 to get a small number of features I will use only occasionally. What is the open source equivalent to XMLSpy?
Originally written in 2004 and now updated to 2012.
XML editors are easy to find. Great XML editors are hard to find. Most are limited by using the proprietary Java. There is no point shouting out that your editing product is open source if the user has to acquire a product with a restrictive proprietary licence.
xmlBlueprint is fast on Windows because it is a native Windows application, not Java. Of course you cannot use a native Windows application anywhere else. I work on some projects where I alternate between Windows, Linux, and Solaris so will not use xmlBlueprint for those projects.