zb0001Len--
		zb0001Mask |= 0x10
	}
	// variable map header, size zb0001Len
	err = en.Append(0x80 | uint8(zb0001Len))
	if err != nil {
		return
	}

	// skip if no fields are to be emitted
	if zb0001Len != 0 {
		// write "BaseOptions"
		err = en.Append(0xab, 0x42, 0x61, 0x73, 0x65, 0x4f, 0x70, 0x74, 0x69, 0x6f, 0x6e, 0x73)
		if err != nil {
			return
		}
		// map header, size 0

	return SRError{Cause: err, Code: ErrInternalError}
}

// SiteReplicationSys - manages cluster-level replication.
type SiteReplicationSys struct {
	sync.RWMutex

	enabled bool

	// In-memory and persisted multi-site replication state.
	state srState

	iamMetaCache srIAMCache
}

type srState srStateV1

// srStateV1 represents version 1 of the site replication state persistence
// format.