훔.. 답변이 상당히 늦었지만
 Lotus Domino/Notes 와 관련된 내용이구요~
 아래의  URL 에서 찾아보시면 되구요..
http://www.notes.net/notesua.nsf/find/inside-notes  관련내용을 인용하면...
  < Notes uses its own databases to control many of its own activities >
 Virtually every computer program uses files that contain configuration and runtime information.
These files do not contain user data; instead, they contain information that controls the operation of
the program. Although Notes needs such files, too, it most often uses its own databases to store this
information.
 There are several reasons to use database files — that is, NSF files — rather than text or binary files,
to hold program data. First, a database contains structured information in the form of notes that
different programs can simultaneously read from and write to. These notes can be copied and then
later replicated. These characteristics are critical in a networked environment where to coordinate
their activities, several Notes programs often need to share data. Second, many Notes and Domino
features are actually implemented as Notes databases, which are easier to understand, upgrade,
port, and deploy than the core Notes and Domino programs, which are written in C and C++. Third,
it implicitly makes many configuration databases accessible over the network, for the simple reason
that Notes databases are transparent and easily accessible over a network connection. This makes
the system that much easier to administer remotely.
 For example, every server in a domain has a replica of the domain’s Domino Directory
(NAMES.NSF), a database that controls the user name space and contains Person documents, Group
documents, public encryption keys, Connection documents that enable and schedule mail routing
and replication, Server documents that contain configuration and restriction settings, and so on.
How Notes works depends on the Domino Directory, which is an NSF file that you can modify and
extend if you have the appropriate access rights. The same is true for several other directory-related
databases that, together with the Domino Directory, give Domino a rich and capable directory
mechanism.
 Almost all of the Notes server tasks — for example, Router, Replicator, Indexer, and so on — read
from and write to one or more Notes databases. In addition to NSF files, other databases play an
important role in how Notes works. The following are a few examples of important client and server
databases that do not have an NSF extension but that do have the same underlying file structure as
an NSF file:
  - Design templates contain design elements, security information, and computational logic and
have the extension NTF.
  - The MAIL.BOX file is on both a mobile client and a server. On a mobile client, the file holds
outgoing mail messages. On a server, the file temporarily stores a message until the Router
moves it to the next stop on the route to its destination.
  - The DESKTOP.DSK file maintains the Notes client workspace — namely, the workspace
pages and the databases on each page.
 이라내요 ^^;;
 ( 어설피 해석하는거보다는 원문을 보는것이 더 나을듯 --; )
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: 저런 확장자가 나옵니다.
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: 정말..
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: 이름이라두 알려주세요...