4D Client uses a "copy" of the structure file that is running on the 4D Server machine. This copy is referred to as the "structure cache" in this Tech Tip.
The structure cache will be located within the user's home directory. For example, given a database named "Test.4DB" running on a server machine with the IP address 10.96.0.79, the structure cache for a user named "Joe" would be located at (on Windows):
C:\Documents and Settings\Joe\Application Data\4D\Test.4DB_10_96_0_79\Test.4DB.REX
On Mac it would be:
Mac HD:Users:Joe:Library:Application Support:4D:Test.4DB_10_96_0_79:Test.4DB.REX
Note that there will also be a corresponding structure resource file with the extension .REA.
The structure cache is updated dynamically, as contents from the original structure are needed. You may have noticed, for example, the first time you load a large picture from the Picture Library it takes some extra time. This is because the image must be downloaded from the server and placed in the client structure cache. This only needs to occur once.