29.1.2 Bond Primitives

Symbol Description
  Default (single or aromatic)
- Single bond (not aromatic)
= Double bond (not aromatic)
# Triple bond
~ Any bond (wildcard)
: Aromatic bond
@ Ring bond
/ Directional single ``up'' bond
Directional single ``down'' bond
/? Directional ``up'' or unspecified
? Directional ``down'' or unspecified