I am impressed by the solidarity of the walkers though. Often, when I've been tricked into walking in the countryside, maybe in a natural park or near some prehistoric site, there are signs to mark the way. Not necessarily those finger posts that tell you how many kilometres it is to the Bronze Age settlement or the spectacular waterfall but just little painted marks or piles of stones to keep you from walking off and becoming benighted as the wolves howl and the wild pigs attack to protect their young.
Some of the marks are there because someone, town halls, provinces or regions, has paid for them to be there. They may or may not be maintained. Sometimes they are there because some association or even an individual thinks it's a good idea, a public service. They're the sort of people that love to be in the fresh air and presume that everyone else does. These marks can be really useful but they can also let you down because they are "unofficial".
There are other paths with marks which are homologated, standardised. These are the ones listed by FEDME, Federación española de deportes de montaña y escalada or the Spanish Federation of Mountain Sports and Climbing. These paths are the GR, PR and SL paths. There are homologation criteria for these paths, rules that say what the characteristics should be and how they should be maintained. The idea is that if you follow one of these trails you won't suddenly be abandoned to your own devices half way up some windswept mountain pass.
The three sets of marks that you will see along these paths are painted flashes on surfaces such as rocks, posts and trees . They are sometimes backed up with piles of stones, little cairns called mojones or hitos. They have colour schemes that tell you what sort of path you are following. Red and white markings for the GR, yellow and white markings for the PR and green and white markings for the SL.
The GR routes are at least 50 kms long are marked with a red and a white flash.
The PR routes are between 10 kms and 50 kms long and are marked with a yellow and a white flash
The SL routes are less than 10 kms long and are marked with a green and a white flash
There is also a turn sign.
Should you ever, mistakenly, wander away from the safety of the asphalt and concrete, with shop windows to look in and signs of civilisation all around, you may come across these strange markings. But don't forget, as Phil Esterhaus used to say, "Let's be careful out there".