BPMN2 — [Meta-model] Exclusive gateway is missing specification of order of leaving sequence flows

Type: Technical

Description of issue: The execution semantics for exclusive gateways correctly states that "the conditions [of the outgoing sequence flows] are evaluated in order". However, the meta-model for an exclusive gateway does not allows for the specification of that order.

Proposal: Using the "appropriate means" (prototype statement?), ensure the relationship from a FlowNode to its outgoing sequence flows is an ordered collection, rather than a set. This provides ordering not only for an exclusive gateway, but for all FlowNodes, but that doesn't seem to harm.
In the XSD, where the sequence flows reference their source node rather than vice versa, an additional attribute or element to render the order may be needed, or the representation of sequence flow in the XSD may need to be revised.

(Assigning to Suzette as representative of MM team who also is concerned with the XSD)

(a) Update Table 8.61 (pg 131)
Append the following to the description for the 'outgoing' association: This is an ordered collection.
The UML Metamodel used as base for XSD and XMI will be updated to reflect this change
Disposition: Resolved