The General Service (GENSER) Security Policy is a sophisticated security policy that is used within the United States. It has many classifications and categories and relationships between them. It is therefore a good policy with which the exercise the security label schema.
A complete description of the GENSER security policy is available here.
The ASN.1 of the GENSER security policy (although slightly different to that described in the above document) is available from the BAE Systems donwload site, in the Certificate Builder and Test Utilities package.
Using the ASN.1 definition, the following XML instance document was created which describes the security policy: genser.xml