Table 4.

How to interpret the values of the constant and boundaryCondition attributes on Species. Note that column four is specifically about reactants and products and not also about species acting as modifiers; the latter are by definition unchanged by reactions.

constant value	boundaryCondition value	Can have assignment or rate rule?	Can be reactant or product?	What can change the species’ quantity?
true	true	no	yes	(never changes)
false	true	yes	yes	rules and events
true	false	no	no	(never changes)
false	false	yes	yes	reactions or rules (but not both), and events