Warmongr....I'll put in my two cents....<br>
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There are basically four divisions of security, from D (the lowest protection) to A (good protection). Within these divisions you will find seven levels though, and each level includes all of the security provisions of the proceeding levels, so that as you can see, levels build upon each other. So in answer to your question, B2 security is simply a level of security a step greater than B1, and A1 is greater than all the other levels. These are simply, as Warcorp points out, orangebook ratings. <br>
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Unfortunately, Warcorp's suspicions are also correct, that the answer is NO to object level security. Your platforms do not follow a physical security model, but rather a discretionary access model. Here the owner of an object controls access to the object for himself, a group, and all others. The owner can do anything with the object, and therefore security is discretionary, and therefore..limited.