https://doi.org/10.1351/goldbook.L03561
A two-dimensional representation of @M03986@ in which atoms are shown joined by lines representing single or multiple bonds, without any indication or implication concerning the spatial direction of bonds. For example, methanol is represented as:
L03561.png
(The term should not be confused with the representation of chemical formulae by the 'Wiswesser line notation', a method of string notation. Formulae in this notation are also known as 'Wiswesser line formulae'.)