A lane is a sub-partition within a process (often within a pool) that runs the length of the process level, either vertically or horizontally. Lanes are frequently used for internal roles (e.g., manager, associate), systems (e.g., an enterprise application), internal departments (e.g., shipping, finance), and so on.
Silver, B. (2009). BPMN Method and Style: A levels-based methodology for BPM process modeling and improvement using BPMN 2.0. In CodyCassidy Press US.