public sealed class ZoneMembershipCondition : IMembershipCondition, System.Security.ISecurityEncodable, 
        System.Security.ISecurityPolicyEncodable, IConstantMembershipCondition {
// Public Constructors
   public ZoneMembershipCondition(System.Security.SecurityZone zone);
// Public Instance Properties
   public SecurityZone SecurityZone{set; get; }
// Public Instance Methods
   public bool Check(Evidence evidence);
// implements IMembershipCondition
   public IMembershipCondition Copy(  );   
// implements IMembershipCondition
   public override bool Equals(object o);        
// overrides object
   public void FromXml(System.Security.SecurityElement e);
// implements System.Security.ISecurityEncodable
   public void FromXml(System.Security.SecurityElement e, PolicyLevel level);
 // implements System.Security.ISecurityPolicyEncodable
   public override int GetHashCode(  );    
// overrides object
   public override string ToString(  );    
// overrides object
   public SecurityElement ToXml(  );       
// implements System.Security.ISecurityEncodable
   public SecurityElement ToXml(PolicyLevel level);       
// implements System.Security.ISecurityPolicyEncodable
}

The ZoneMembershipCondition class uses the value of Zone evidence to determine if an assembly or application domain qualifies for membership of a CodeGroup. The SecurityZone property contains a member of the System.Security.SecurityZone enumeration that identifies the security zone required for membership. The initial value of SecurityZone is set in the ZoneMembershipCondition constructor.

When policy resolution calls the Check( ) method, the ZoneMembershipCondition enumerates the provided Evidence collection to determine if it contains Zone evidence. If so, the ZoneMembershipCondition compares the value of its SecurityZone property with the value of the Zone.SecurityZone property. If the two values match, the assembly or application domain is granted membership of the CodeGroup.