categories within projects

i see that this is not possible at the moment but would be good as a feature request. I would like to put in categories eg.
Project> Pre-Production
— Category> Script writing
— Task> write scene 1
— Task> write scene 2
— Category> Storyboard
— Task> find illustrator
— Task> mask items
Project> Production
— Category> Filming on location 1 ……..

Unless you know a work around for this?