ALONG NM 35, in the southern range of the Gila National Forest, a sign shaped in the National Forest Service’s trademark trapezoid bears a question mark. No words. No arrows. Just that. Puzzled? You’re not alone. It’s one of the questions forest rangers get at the district offices that the signs subtly point toward. “You might find that sign in multiple locations around the forest,” says spokeswoman Maribeth Pecotte. “It’s a national recreation symbol for finding information.”

In the same way that you might see a sign with a pair of hikers to indicate a trailhead, or a tent symbol for nearby camping, the question mark signifies: Ask questions ahead. “We’re trying to come up with a universal language that tells people what we’re offering without using words that everyone might not be able to read,” Pecotte says. With hundreds of miles of trails throughout the Gila’s 3.3 million acres, rangers encourage questions. “Anyone planning a trip will want to plan ahead and know what they’re getting into,” Pecotte says. “It can swallow you up. Be well prepared if you decide to visit.”

Look for the question mark signs when you travel in the Gila National Forest.