secure modes- clearance vs access approval

[CISSP_Candidate]

I sat down to learn something about the different security modes and now I’m confused by the terms ‘proper clearance’ and ‘formal access approval’. There must be a difference but I didn’t realize it.




"I don’t understand how I can get a clearance for ALL information on the system although I only have an approval for SOME information."

Because the information is in different compartments (think of boxes of informations).
A system might required you to have Top Secret clearance for Allthe information but doesn't mean that you have access (approval) or need to know to all the information in all the compartments. Some compartment (boxes) might required additional approval steps before you can read or access that information.

http://usmilitary.about.com/cs/generalinfo/a/security.htm

[Jescoi]

from the above link "TOP SECRET: Applied to information or material the unauthorized disclosure of which reasonably could be expected to cause exceptionally grave damage to the national security.
In addition to the above, some classified information is so sensitive that even the extra protection measures applied to Top Secret information are not sufficient. This information is known as "Sensitive Compartmented Information" (SCI) or Special Access Programs (SAP), and one needs special "SCI Access" or SAP approval to be given access to this information."