The SMART .notebook format is simply a zipped set of XML and SVG files, This may be common knowledge but it is certainly the first time I have come across it.
To test it you can create a file in SMART Notebook rename the extension from .notebook to .zip, double click to open, you will be presented with several files named page_n_.svg where _n_ is a number, as well as a series of other files and folders including settings.xml, preview.png and metadata.xml.
The XML and SVG files can be edited in notepad, or perhaps more useful for the SVG files in a program such as Inkscape.