In law, "compound substances" may incorporate both unadulterated substances and blends with a characterized organization or assembling process. For instance, the EU guideline REACH characterizes "monoconstituent substances", "multiconstituent substances" and "substances of obscure or variable sythesis". The last two comprise of numerous compound substances; be that as it may, their personality can be set up either by direct synthetic investigation or reference to a solitary assembling process. For instance, charcoal is a very perplexing, to some degree polymeric blend that can be characterized by its assembling cycle. In this manner, albeit the specific compound personality is obscure, distinguishing proof can be made to an adequate exactness. The CAS file likewise incorporates combinations.