This attribute is used at both the resource and the portion levels.
A single indicator of the highest level of classification applicable to an information
resource or portion within the domain of classified national security information.
The Classification element is always used in conjunction with the Owner Producer element.
Taken together, the two elements specify the classification category and the type
of classification (US, non-US, or Joint).
It is manifested in portion marks and security banners.
PERMISSIBLE VALUES
The permissible values for this simple type are defined in the Controlled Value Enumeration:
CVEnumISMClassificationAll.xml