KDE PIM has a large and diverse code base. It also has a lot of different contributors, and (gladly!) accepts patches from outside the core community as well. However, to keep the code base sane and readable, there are coding standards which apply to various parts of the KDE PIM code. When you write a patch or contribute code, remember to follow these guidelines or you run the risk of your contribution being rejected. We don't like to reject things based on form, but it's got to be done to keep things readable in the long run.
First off, there are the general guidelines that apply to all of KDE. I can't find them now, but they boild down to:
KMail, KOrganizer, KNode, libkcal and libkabc have one single coding style. It's a no-tabs, K&R brace style coding style.