Information Integrity

Exploration Stage: Post Office
From: Mr. Black
Description: It's common practice among lamplighters to make marks and signs for themselves. But his memory won't recover simply by looking at the symbol. We need to find something else marked with it. There will be information about why Carlos Light changed his route near it. Let's draw the sign first. Surely there's paper in the post office...
Completed: Carlos Light! Give me your hand. Keep it straight so that we can see the sign clearly.