Hi Miboje. I should have been more clear, sorry. A cache sign or symbol can look like anything as long as it leads you to a cache. So the only way you know that you have a cache symbol is if you recover the cache. However, if you're finding the type of symbols you read about on tnet, hearts, drill holes, triangles, etc., you have to hit the books and try to find out why somebody would create an organized setup using those symbols, at that spot. Most people don't get that far. It's more fun to look for signs in the field.
The site I mentioned above used the heart and I spent countless hours of research and interviews to come to the conclusion that the site could have been a cache site. But I still have no proof because I made no recovery and never will, because of where it's located.
From what Orangeman has posted, he has found carvings on stone that could indicate an organized effort to hide something. Now he has to find out the who, when and why of the location.