An early line notation for chemical structures. The symbols used are the upper-case letters of the alphabet (A-Z), the numerals (0–9), with three other symbols: the ampersand (&), the hyphen (-), and the oblique stroke (/), and a blank space. Atomic symbols with one letter, such as B and F, are unchanged. Frequently occurring elements with more than one letter and functional groups are also assigned one letter; for example, G stands for chlorine, Q for hydroxyl, and Z for NH2. The numerals indicate the number of carbon atoms in an unbranched internally saturated alkyl chain. For example, CH3 is denoted 1 and CH3CH2 is denoted 2. To establish the notation of a compound the characters for the fragments are given in an established order. For example, the notation for C2H5OH is Q2. Rules for structures with branched chains and fused rings are also given. WLN provides a short and unambiguous notation, which is suitable for database searches.