addconstraint[options] adds a constraint to the current model. Options are the same as constraintToSBML.
addconstraint[x, options] is the same as addconstraint[id→x, options].
modifyconstraint[options] modifies a compartment type in the current model. Options are the same as constraintToSBML.
modifyconstraint[x, options] is the same as modifyconstraint[id→x, options].
removeconstraint[id] removes a compartment type with the given id from the current model.addconstraint, removeconstraint, modifyconstraint new in 2.6.