How should I begin trying to reverse engineer this file format? The only thing I can think of is saving a simple file, and then dig in with a hex editor. But since the file format may be some kind of archive, that seems like the wrong approach. I've always been a little interested in the idea of reverse-engineering a file format, but I never actually attempted it. How should I begin?
In particular, I am interested in Smart Notebook which loads and saves data into .notebook files. This is an undocumented proprietary file format. SMART is the leading manufacturer of white boards and their notebook software is therefore one of the most popular formats for educational (presentation) content. There is an open standard for whiteboard files and Open Sankore is an open source program that can open and save them. However, Smart Notebook is not fully compatible with the open whiteboard format so I really would like to understand the .notebook file format so that I can write software that makes use of it. The open stand (.iwb files) are zip archives that contain images and SVG data. It occurs to me that .notebook files may also be compressed or at least contain a number of sub-files within it (like images and swf files).