gistfile1.xml

<request method="invoice.create">
	<invoice>
		<client_id>2</client_id>
		<lines>
			<line>
				<name>Time Entry</name>
				<time_entries>
					<time_entry>
						<time_entry_id>14</time_entry_id>
					</time_entry>
					<time_entry>
						<time_entry_id>16</time_entry_id>
					</time_entry>
				</time_entries>
			</line>
		</lines>
	</invoice>
</request>