Environmental labelling may be categorized in many ways: mandatory labelling and voluntary labelling (in terms of binding degree), national environmental labelling and international labelling (in terms of scope of application), and Process and Production Methods (PPMs) labelling and Non-Process and Production Methods labelling (in terms of PPMs). For the purpose of our study, we have divided it into three categories: the government-initiated mandatory, the government-initiated voluntary and the private-initiated voluntary environmental labelling. (The rest is omitted.)