E–Z notation

E–Z configuration, or the E–Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry.

The letters E and Z are conventionally printed in italic type, within parentheses, and separated from the rest of the name with a hyphen.

For organic molecules with multiple double bonds, it is sometimes necessary to indicate the alkene location for each E or Z symbol.

For graphical representations, wavy single bonds are the standard way to represent unknown or unspecified stereochemistry or a mixture of isomers (as with tetrahedral stereocenters).

A crossed double-bond has been used sometimes; it is no longer considered an acceptable style for general use by IUPAC but may still be required by computer software.