BPMN (Business Process Model and Notation) is a "Model" and a "Notation." The word "Model" may remind you of "organizational models" or "model estimates." Simply put, a model is a simplified version of something. So they don't have to be overly detailed. How detailed business process models should be defined depends on the workflow system or BPM system that is being used. Most process models include three types of data: flow information, person-in-charge information, and the data set. Today let's look at two types of "split conditions," which are a basic flow information.
BPMN Sample: XOR Split
You may be able to understand the above workflow intuitively. The diamond-shaped icon on the left represents the split condition. Notice the "X" mark inside the icon; this "X" indicates only one of the flows are followed. In other words, after the first task, the flow goes to either 2a, 2b or 2c. This is called an "XOR split." It might be easy to understand it as a train that hits a fork in the track and follows only one route.
BPMN Sample: AND Split
In the below workflow, however, there is a "+" mark within the diamond-shaped icon. This means all flows are followed. In other words, after the first task is completed, the "senior staff," "leader" and "executive" are all allocated their tasks, which are executed concurrently. With the train analogy, this means the train splits into separate cars and follows all possible routes. This type of split is called an "AND split," "parallel split," "parallel routing," etc.
By the way, in reality the AND split is rarely ever used. It causes a headache when one of the routes needs to loop back to the previous task. So, you'll probably be okay as long as you remember just the XOR split. Brush up your Process!!