The Opera Show Format (OSF) is a set of conventions used in a web page using XHTML 1.0 Strict and CSS 2.1.
The entire presentation, including all slides and images (in data: URIs) is contained in a single file.
The Slide Show (S9) Ruby gem creates OSF-compatible presentations using a wiki-style markup language.
[6] Other tools include the Windows-based QuickShow,[7] and the Project Velt[8] Opera widget.
An older version is available at the personal site of Opera Software's CTO, Håkon Wium Lie.