CVS Update problem with "."

[Sundeep]

1. I checkout the module inside the directory, say A.
2. Now if my module is "fun"... then I have A/fun...
3. I am in the directory A
4. I run this update command:
    a) command : cvs -f update -j 10 -kk .
      Result is nothing... cvs simply return back

   b) % cvs -f update -j 10 -kk ./
    Result is nothing... cvs returns

   c) % cvs -f update -j 10 -kk
     Result is that update happens succesfully.

cvs update: Updating fun
cvs update: Updating fun/src
cvs update: Updating fun/src/java
U fun/src/java/AppA.java
U fun/src/java/AppB.java
U fun/src/java/AppC.java
U fun/src/java/AppD.java
U fun/src/java/AppE.java

The difference is only a ".", which accordingly means current
directory.

Why does CVS behave differently when I give "." or when I do not give
"."

Note:
If I go into fun and run same command with ".", everything works fine.

I can understand that as fun will have CVS/ directory... cvs may work.

But my concern is if I am out of fun... means in parent directory of
fun (A/) then why it behaves differently for "." and NO "."