Janitrol 18-60 thermostat. What is the W2 wire for? Also, where do the rest of the wires go in a new programmable one?

Thanks to all posts. I finally found the "sticky" that explains the color codes. Now to get the correct thermostat

w2 probably for heat
If you look at the old tstat and tell us what each color is attached to it will help
Tag or write down what each color is attached to before you remove,will save you a bunch of headaches