This seems quite clear to me, though perhaps a bit abstract.

Thanks!

Clear! Clear!! My pain is over!!No more documentation for a while!

I'll do examples for the CPAN release.

I thought that the spreadsheet comparison is a bit too simple because it does not involve any kind of tree structure

Not a spreadsheet comparision, but spreadsheet + XML. Both structure and calculations in one package.

Thanks for the help, both you, dragonchild, Arunbear and the people helping before! I need help when it comes to documentation.