EZ NotationTo a certain extent, the Z configuration can be regarded as thecis-isomer and the E as the
trans-isomers. This correspondence is exact only if the two carbon atoms are identically
substituted.
In general, cis-trans should only be used if each double-bonded carbon atom has a hydrogen
atom (i.e. R-CH=CH-R’).
IUPAC Gold book on cis-trans notation.^1
IUPAC Gold book on E-Z notation.^2
1 http://goldbook.iupac.org/C01093.html
2 http://goldbook.iupac.org/E01882.html