Look down at British roads and pavements and there's often a slew of squiggles, dots and arrows, painted in a plethora of hues. But what do they actually mean?
In London alone, more than 50 different utility companies have the power to dig up the highway.
There are a lot of people who need to know exactly what lies beneath the ground, says Stephen Palmer, the chief executive of the Institute of Highways Engineers.
Mistakes are dangerous and costly. To offset such risks, a language has emerged that is spoken in spray paint. Its lexicon is numbers, lines and symbols. Its grammar is most definitely colour.
And once understood, this pavement patois - based entirely on convention rather than law - puts even a basic speaker in touch with a subterranean myriad of pipes and cables powering the ebbs and flows of modern existence.