Some main-chain scissions are classified according to the mechanism of the scission
process: hydrolytic, mechano-chemical, thermal, photo-chemical, or oxidative scission.
Others are classified according to their location in the
backbone relative to a specific structural feature, for example, α-scission (a scission of
the C–C bond alpha to the carbon atom of a photo-excited carbonyl group) and β-scission
(a scission of the C–C bond beta to the carbon atom bearing a radical), etc.