On this Wiki, nosoy products contain no soy and are not suspected to be contaminated.
Potentially tainted products naturally contain no soy, but may have been processed in a facility that also processes soybeans.
Soy alert products contain a significant amount of soy and can present serious health issues for people with soy allergies. Examples include many foods that include soy lecithin or soybean oil (often identified as simply vegetable oil).
Taboo products are principally composed of soy. Eating anything you even suspect to be such a product can be dangerous. For instance, the icing on many snack cakes is little more than sugar mixed with soybean oil. Tofu is made from soy.