Question about "trust files on remote computers..."

[androute]

There is a suboption for Network Scanning, in Symantec Antivirus Corporate Edition to "trust files on remote computers running Auto-Protect".
In the help it says that "For protection, you may not consider it necessary to check the Enable scanning option if you have enabled Auto-Protect on all of your servers. For example, if network scanning is enabled on client A and Auto-Protect is also enabled on server B, when client A writes a file to a network drive on server B, Symantec AntiVirus scans the file on client A and scans the file again on server B. You should be aware that this repeat scanning is likely to reduce network performance on the client computer."

I was wondering : is the distinction client/server purely made on the OS type (eg. Windows Server 2003 vs XP ?) or is any machine that has a file locally a server in this context, and any machine that accesses the file a client in this context ?

In other words, if I copy a file from an XP machine to a 2003 Server machine, and I initiate the copy from the 2003 server, is this then considered to be a client in this context or not ?