questions on contact files

[it lx]

Hi all,
     I've ran through briefly on the imp's coding. Can someone please 
enlighten me as

1. Why are there 2 php files (contacts.php3 and addcontact.php3) instead of 
1?
2. What different tasks do they handle? How about the contactsFrame.php3 and 
contactsLdapFRame.php3?
3. How many frames are there at the contacts.php3 interface?
4. Is Imp depending on Ldap to retrieve data from the folders as well as 
from the database?

   Thank you.
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