NOTE: These are abstractions of terms I think should be added, not absolutes. The details of these implementations, especially naming, are definitely up for debate, please give feedback!
reactionDirection is difficult to specify. MetaCyc has the same problem, because I contacted them about ambiguities in their data; in essence, all reactions are presumed to be reversible under the right conditions. You could use "Physiological left to right", for example, but what constitutes physiological is difficult to define (e.g., thermophile vs psychrophile). If we do add directions, we should specify rather than just , as that is, perhaps, ambiguous.
NOTE: These are abstractions of terms I think should be added, not absolutes. The details of these implementations, especially naming, are definitely up for debate, please give feedback!
Reaction -> isBalanced -> (true,false)^^xsd:boolean Reaction -> reactionDirection (\<Left>, \<Right>, \<Bidirectional>)^^Specifier
These two new predicates would simply make it possible to describe a reaction with even more detail.