This keynote will provide a general case study on XML usage within the open source community. The main goal is to show the diversity of usage, and of the associated tool chains. During the presentation, we will cover:

- web site build, XSLT processing, Web server integration

- file formats for simple records like user preferences, font configuration

- exchange formats for word processors, spreadsheet

- documentation, with a special focus on DocBook

In parallel this will allow us to point to the various Open Source XML solutions available, and their usage within communities such as the

Gnome, KDE, Apache and XFree86 projects.