It's the day after Christmas and time to hook up, assemble, attach, connect and install all those wonderful presents under the tree. Many are complex electronic products that bear a number of mystery symbols that have important meaning. They're there for a reason. Some are yellow triangles with a black outline. Those with a lightning bolt mean there's risk of electrical shock; three wavy lines indicate the surface is hot; and an exclamation point means stop and read the instructions. There are currently 800 such symbols created by the International Electrotechnical Commission to standardize everything from identifying connections and operational functions to installation terminals and safety warnings. Another important label is the UL circle indicating that the product has been tested and approved. And that's the On The House Tip for today.