Thieves Cant

Thieves Cant is a less a unique language primarily used by criminals and spies that uses a series of symbols and terms that allow those who understand it to engage in hidden conversations whilst in the presence of others. 
The spoken element of Thieves Cant is often commenced through trigger words signifying the speaker as fluent in the language and aware of the allegiance or hidden role of their subject. It follows as a conversation that on its surface appears normal and contextually appropriate in either Common or the local language but is in fact of an entirely separate matter. 
The written element consists of a range of symbols and markings which designates messages ranging from "Safe House" to "Good Loot Within" that are marked on structures and landmarks across Aesalia. These marks are universal across the planet left unchanged through an honour among thieves.