Start where work changes hands
A department chart shows responsibilities at a high level. A process handover map can show what one person needs from another, who accepts the output and what evidence supports that decision.
Ask the receiving person
In a fictional workshop, dispatch may need more than a completed repair status. It may need a job reference and confirmation of the final check. Ask the person receiving the work what is sufficient and what is often missing.
Walk a real example
Follow the work with the people involved. Use their explanation to test whether the map reflects actual decisions. Keep the map simple enough to remain useful when the process changes.