Definition: Stoichiometric coefficient of a physical entity in the context of a conversion or complex. Usage: For each participating element there must be 0 or 1 stoichiometry element. A non-existing stoichiometric element is treated as unknown. This is an n-ary bridge for left, right and component properties. Relative stoichiometries ( e.g n, n+1) often used for describing polymerization is not supported.
Source:http://www.biopax.org/release/biopax-level3.owl#Stoichiometry