As Derek Miers commented on one of my old blog, some of my BPM maps were not compliant to BPMN. He was for sure right, and I bought the book 'BPMN Modeling and reference guide' that I really encourage people to buy and read to be fluent around BPMN. I was short cutting the approach by looking at presentations you can find on the web. You can get your own interpretation of the notation and got completly wrong. So a reference is always preferable, and with this knowledge you may arrive to design good process, at least process compliant to the intent of this standard.
The book is a must to be sure every one understand what a BPMN diagram is representing. Each BPMN modeler tool on the market has his own interpretation or 'add-on' so it is always interesting to get back to the intent of the notation and the reference. The book is illustrated with a lot of samples. Very useful.
Thanks again Derek.