Understanding Phonebook xml file.

[itgs]

I know that in the provisioning folder, there are various files and, specifically, the phonebook xml files used in phones templates as remote phonebook (aastra_phonebook.xml, cisco_phonebook.xml, yealink_phonebook.xml, etc..)

I noticed the following two files:

3CXPhone-directory.xml
000000000000-directory.xml

What are the difference and what is the purpose of that files ?

I added a new contact, using the 3CX V15 web interface, in the general phonebook and noticed that all the phonebook files was updated with the entry.

Is it normal ?

Last question...:
where is the phonebook file used by the 3CX Client (windows) ?

Thank you for support and for help me to understand