Central Buffer Node
A Central Buffer Node is an object node for managing flows from multiple sources and destinations, represented in an Activity diagram. It acts as a buffer for multiple in-flows and out-flows from other object nodes, but does not connect directly to Actions.
OMG UML Specification:
The OMG Unified Modeling Language specification, (v2.5.1, p.398) states:
A CentralBufferNode acts as a buffer between incoming ObjectFlows and outgoing ObjectFlows. It accepts all object tokens offered to it on all incoming flows, which are then held by the node. Held object tokens are offered to outgoing flows according to the general ordering rules for ObjectNodes. When an offer for a token is accepted by a downstream object node, that token is removed from the CentralBufferNode and moved to the accepting object node, as for any object node.