SYSML2 — TransitionUsage effectAction attribute text and constraint are different

In Clause 8.3.17.9 (TransitionUsage), the Attributes section says effectAction are expressions:

Attributes
/effectAction : ActionUsage [0..*] {subsets feature}
The ActionUsages that define the effects of this TransitionUsage, which are the ownedFeatures of the TransitionUsage related to it by TransitionFeatureMemberships with kind = effect, which must all be Expressions.

but a constraint says they're action usages

deriveTransitionUsageEffectAction
The effectActions of a TransitionUsage are the transitionFeatures of the ownedFeatureMemberships of the TransitionUsage with kind = effect, which must all be ActionUsages.
triggerAction = ownedFeatureMembership->
selectByKind(TransitionFeatureMembership)->
select(kind = TransitionFeatureKind::trigger).transitionFeatures->
selectByKind(AcceptActionUsage)