If Oem Schema shall also expose in "/redfish/v1/$metadata"?

Hi,

Thanks for taking time to explain everything for me. 

I created a Oem schema for my Oem extension URI, does it also need to expose in "/redfish/v1/$metada" resource?
If yes, would you provide a example of how to reference a OEM extension?

[example response of my Oem extension URI]
{
"@odata.context": "/redfish/v1/$metadata#OemTest/$entity",
"@odata.type": "#OemTest.v1_0_0.OemTest"
"@odata.id": "/redfish/v1/OemTest",
...
Customize properties...
}

[for the item : edmx:Reference, does it mean I need to establish a server(http://contoso.org/Schema) like DMTF Schemas(https://redfish.dmtf.org/schemas/) to list supporting schema files ? ]
<edmx:Reference Uri="contoso.org/Schema/OemTest.xml">

<edmx:Include Namespace="OemTest"/>

</edmx:Reference>