Smokewriting

Isturians have developed a method of communication that can be used to transmit messages from one mountain peak to another. In ancient times, the Isturian people used a variety of different materials to produce different colours of smoke when added to a bonfire, and rudimentary methods of covering the flames to convey simple messages.
In every town and city, there is usually one bonfire, often in the form of a Smoketower, that is keep alive constantly for cases of emergency signals. These are operated by ruling authorities, who have been charged with its maintenance. Signals are particularly effective when used atop towers or mountain peaks, as they are visible for hundreds of miles.

System

Colours

	Meaning	Compound
Black	Warning, be prepared	Crude oil, "dirty" mixtures
White	Casual or friendly message	Green, wet materials
Red	Emergency, with haste	Lithium-based formula
Blue	Unusual or unexpected message	Oil-based compound with potassium nitrate

Pattern

	Meaning
1 puff
2 puffs
3 puffs
2 puffs with long gap
1 puff, a gap then 2 puffs
2 puffs, a gap then 1 puff
2 puffs, a gap then 2 puffs

Utility

Nowadays, the Isturian people have developed specific compounds that increase the visibility and range of the colours of smoke produced by bonfires. There are also mechanisms that have been engineered specifically to blot out the smoke as easily as possible to convey the message.