Fischer projection (Fischer–Tollens projection)

https://doi.org/10.1351/goldbook.F02391
A projection formula in which vertically drawn bonds are considered to lie below the projection plane and horizontal bonds to lie above that plane. Thus for the molecule Cabcd:
F02391.png
Sources:
Blue Book, p. 484 (http://www.acdlabs.com/iupac/nomenclature/)
PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2208 (https://doi.org/10.1351/pac199668122193)