CA driver's license

As a resident of California I am obliged to have a Californian driver's license if I want to drive (legally) cars here. Even though I have my national driver's license for many years now, still I have to take both written test and driving test to get the Californian one. I just started studying for the written exam and I just can not stop myself from sharing with you this very interesting rule that I found in the official CA driver's handbook: "Do not shoot firearms on a highway or at traffic signs". Hmm, does it mean that you can shoot firearms at roads which are not highwyas and at all other things that are not traffic signs?