In the Process Explorer, the process paths that start from the activity 'Process Start' or end at the activity 'Process End' are denoted by dotted lines.

In the given example, you will see that all the paths/links that start at 'Process Start' are being represented by dotted lines.

1. Process Start - Create Purchase Requisition Item
2. Process Start - Create Purchase Order Item
3. Process Start - Scan Invoice

Also, the paths/links that end at the activity 'Process End' are being represented by dotted lines.

1. Book Invoice - Process End
2. Scan Invoice - Process End
3. Receive Good - Process End
4. Block Purchase Order Item- Process End

This is true considering its a single event log. In multi event logs, dotted lines may be also represented by paths/links in between two activities interlinking different event logs.

The dotted connections point to start-/end-activities. They are not actual paths but a way to distinguish what are the starting or ending activities in a certain process flow.