ziles pseudo code.

compos-main.zul.xml

<?init class="org.zkoss.zk.ui.util.Composition" arg0="/compos-template.zul" ?>
<zk>
	<window self="@define(content)" title="window1" width="100px" />
	<window self="@define(content)" title="window2" width="200px" />
	<div self="@define(detail)" width="300px" height="100px">
		<div apply="org.zkoss.bind.BindComposer"
			viewModel="@id('inner') @init('org.zkoss.ziles.web.Case0ViewModel')">
			<hlayout>
				<textbox value="@bind(inner.userName)" />
				<label value="@bind(inner.userName)" />
			</hlayout>
		</div>
	</div>
</zk>

compos-template.zul.xml

<window title="template" border="normal">
	<hbox>
		<hbox self="@insert(content)"/>
		<hbox self="@insert(detail)"/>
	</hbox>
</window>

index1.zul.xml

<?page title="Page0"?>
<zk>
	<ziles id="layout" layout="/testcase/layout/layout1.zul" width="100%" height="100%">
		<custom-attributes ziles.title="Page 0 on Title" ziles.footer="Page 0 on Footer"/>
		<template name="ziles.header" src="/testcase/layout/header.zul"/>
		<template name="ziles.footer" src="/testcase/layout/footer.zul"/>
		<template name="ziles.body">
			<div>
				This is page 0
			</div>
		</template>
	</ziles>
</zk>

index2.zul.xml

<zk>
	<ziles layout="/testcase/layout/layout1-defval.zul" width="100%" height="100%">
		<custom-attributes ziles.title="Page 1 on Title"/>
		<template name="ziles.body">
			<div>
				This is page 1
			</div>
		</template>
	</ziles>
</zk>

layout1-defval.zul.xml

<zk>
	<!--layout with default value -->
	<ziles layout="/testcase/layout/layout1.zul">
		<custom-attributes ziles.title="Zk Application Title" ziles.footer="Zk Application Footer" />
		<template name="ziles.header" src="/testcase/layout/header.zul"/>
		<template name="ziles.footer" src="/testcase/layout/footer.zul"/>
	</ziles>
</zk>

layout1.zul.xml

<zk>
	<vlayout width="400px">
		<div id="header" ziles="@replace()">
			Header here
		</div>
		<window id="body" ziles="@replace() @target(div)">
			<hbox>
				<div >
					Body here
				</div>
			</hbox>
		</window>
		<div id="footer" ziles="@replace()">
			Footer here
		</div>
	</vlayout>
</zk>