This term denotes a plurality of atoms which connect specified groups or atoms. The atoms of the chain must be nonionically attached to each other and to the specified groups or atoms. If the chain may not include any ring members it will be designated as acyclic. When the chain may include ring members the title will state that the chain may include a ring. The chain ends where it attaches to the specified groups or atoms and does not include any part of them. The chain may have substituents but the substituents are not part of the chain.