- Single, double, triple and quadruple bonds are indicated by one, two, three and four lines, respectively.
- A circle within a ring indicates that all the ring bonds have the aromatic bond type.
- If some, but not all, bonds in a ring have the aromatic type (which is not chemically reasonable but can happen), no circle is displayed in the centre of the ring but each aromatic bond is indicated by a small red circle going through the bond.
- Pi bonds to metals are indicated by single broken lines.
- Delocalised bonds are indicated by double broken lines.
