While on Flickr.com the other day I saw a photo taken by Peruvian photographer Christian Vinces, which illustrated how thieves/burglars use their own form of hieroglyphic-esque code to identify potential targets. As the photo shows below this is done on the target home/building itself usually with the use of chalk, pen, pencil or even a chisel/screwdriver. These drawings help the other burglar associates understand the possible dangers they might face once inside the property or know how many people occupy the dwelling along with the hours that they are normally present. The fact that this information is public now probably means that they have adapted and altered their code to protect their illegal activities.
The symbols in the photo on the right side cover the following: big dog, not very interesting, easy in the morning, easy at night, their away - no difficulties, old woman alone all day, easy in the afternoon, children alone in the morning, abandoned, woman alone, home of rich people, children alone in the afternoon, good objective, recently observed, very interesting/lucrative, and home of businessman
On the left of the photo the following symbols mean: Unoccupied home + the months unoccupied, generous people, don't bother/insist, people available, Sundays, and nights