Leo is... * A general data management environment. Leo shows user-created relationships among any kind of data: computer programs, web sites, etc. Leo shows multiple views of data within a single outline. * An outlining editor for programmers. Leo supports optional noweb and CWEB markup. * A flexible browser for projects, programs, classes or any other data. * A project manager. * Fully scriptable using Python. * Leo's outline files are XML format.
SLiP is a quick, alternative syntax for creating and editing XML data by hand and if you know Python, it should also be familiar. not my cup of tea but has a nice comparison of other lightweight xml notations