cluster

type Block struct {
	Header  *flow.Header
	Payload *Payload
}

type Payload struct {

	// Collection is the collection being created.
	Collection flow.Collection

	// ReferenceBlockID is the ID of a reference block on the main chain. It
	// is defined as the ID of the reference block with the lowest height
	// from all transactions within the collection. If the collection is empty,
	// the proposer may choose any reference block, so long as it is finalized
	// and within the epoch the cluster is associated with. If a cluster was
	// assigned for epoch E, then all of its reference blocks must have a view
	// in the range [E.FirstView, E.FinalView]. However, if epoch fallback is
	// triggered in epoch E, then any reference block with view ≥ E.FirstView
	// may be used.
	//
	// This determines when the collection expires, using the same expiry rules
	// as transactions. It is also used as the reference point for committee
	// state (staking, etc.) when validating the containing block.
	//
	// The root block of a cluster chain has an empty reference block ID, as it
	// is created in advance of its members (necessarily) being authorized network
	// members. It is invalid for any non-root block to have an empty reference
	// block ID.
	ReferenceBlockID flow.Identifier
}