From Martin Haller, Software-Engineering:
HM XColdo is a browser extension for MS Internet Explorer and Firefox you can use to create and edit 'HM Collection' documents right from within your Web browser. 'HM Collection' documents are XML documents containing a data collection with any desired content (link lists, image lists, recipe collection, item lists, price lists, address lists, and so on). Such an XML document is viewable in any Web browser like a usual HTML document. 'HM Collection' documents are stored as local XML file on your computer.
To store your data in the vendor independent, open XML document format is in your interest because you will be able to view and edit these documents with any Web browser or text editor program, respectively, still in the future, even though HM XColdo might not be available then. Moreover, XML data can easyly be converted into another data format.