A stereochemical projection for an acyclic molecule (or portion of a molecule) where the main chain is represented by a zig-zag line in the plane and the substituents are shown above or below the plane.
Source:
PAC, 1996, 68, 2193
(Basic terminology of stereochemistry (IUPAC Recommendations 1996))
on page 2222
Transformed and rewritten from PDF version (entry
http://www.iupac.org/goldbook/Z06747.pdf)
by: Miloslav Nic, Jiri Jirat, Bedrich Kosata, ICT Prague, Czech Republic