The maximum end-to-end distance of a @L03556@ chain. For a @S05694@ molecule, this usually means the end-to-end distance of the chain extended to the all-@C01092@@C01258@. For chains with complex structure, only an approximate value of the contour length may be accessible. The sum of the lengths of all skeletal bonds of a @S05694@ molecule is occasionally termed 'contour length'. This use of this term is discouraged.