proc ModifyFlowLineRateHlt { trafficItemName endpointSetName rate } {
    # trafficItemName = The Traffic Item Name in exact spelling
    # endpointSetName = The endpointSet name
    # rate            = The percentage number

    set trafficItem [GetTrafficItemByName $trafficItemName]
    puts "\ntrafficItem: $trafficItem\n"

    if {$trafficItem == "" || $trafficItem == "0"} {
	puts "\nError ModifyFlowLineRateHlt: No such Traffic Item name: $trafficItemName"
	return 1
    }
    
    set highLevelStreamId [GetEndpointSetHandle $trafficItem $endpointSetName]
    if {$highLevelStreamId == 0} {
	puts "\nGetEndpointSetHandle: No such name found in flow group in Traffic Item $trafficItemName: $endpointSetName\n"
	return 1
    }

    puts "\nModifyFlowLineRateHlt: $highLevelStreamId : rate = $rate"
    set status [::ixia::traffic_config \
		    -mode modify \
		    -stream_id $highLevelStreamId \
		    -rate_percent $rate \
		   ]
    
    if {[keylget status status] != $::SUCCESS} {
	puts "\nError ModifyFlowLineRateHlt: $status\n"
	return 1
    }

    return 0
}