Umbramarks

Umbramarks are the sigils etched into surfaces that the Thieves' Union uses to communicate with each other.

''A crudely etched cat into the eaves of a white-washed cottage decorated with hanging flowerpots indicated a kindly woman lived there, and to tell a pitiable story. An X inside a circle on another home indicated there was nothing worth stealing inside. A few indicated that survival would be difficult if you tried, while some, more than I anticipated, claimed the house paid the thieves’ guild for protection. For others, X marked the spot of treasure.''