XML schema help for an XML document

> ______________________________________________ 
> From: 	Manikandan Thangavelu  
> Sent:	27 April 2008 21:27
> To:	'xmlschema-dev-request@w3.org'
> Subject:	XML schema help for an XML document
> 
> Hi All,
> 
> I am trying to develop an XML schema for an XML file which is used to
> build the UI for an application.
> I have an issue in it.In one of my XML tags there are two attributes
> out of which one is mandatory and presence of both are mutually
> exclusive.If one of those attibbute is present, then the other should
> not.Follwing is the sample of my XML
> 
>     <Menuitem name="_Contents" ID= "ID_CONTENTS" Description="Help
> Contents." />
>     <Menuitem name="_Index" ID= "ID_INDEX" Description="Help Index."
> />
>     <Menuitem name="_Search" ID= "ID_SEARCH" Description="Help
> Search." />
>     <Menuitem name="_About Me" ID= "ID_ABOUT_Me"
> Description="VeriCentre version information and Add-on(s) installed."
> />
>     <Menuitem name="_Notepad" ApplicationPath="C:\Windows\notepad.exe"
> Description="Opens the notepad application."/>
>     <Menuitem name="Adobe" ApplicationPath="C:\Program
> Files\Adobe\Adobe.exe" Description="Open Adobe"/>
> 
> 
> Among the attributes for Menuitem either "ID" or "ApplicationPath" is
> mandatory.If "ID" is there, then "ApplicationPath" should not be and
> if "ApplicationPath" is there, then "ID" should not be.
> 
> How can I develop a schema for this case?
> 
> Thanks in Advance,
> Manikandan