The terminal 21n supplies the server 23 with the generated update information through the network 22.
The server 23 extracts the user ID “A002” and the file ID “0000540” from the update information supplied from the terminal 21n through the network 22. The server 23 reads out user information including the thus extracted user ID and the file ID from the not shown built-in storage section.
The server 23 then compares the read out user information with the update information from the terminal 21n, changes the read out user information based on the comparison result, supplies the not shown built-in storage section with the changed user information, and stores the user information therein in an overwrite manner.
Specifically, suppose a case where, for example, the user information read out by the server 23 includes the user ID “A002”, the file ID “0000540”, the view range “25-75”, a caret position “50, 9”, the data “Hel” being currently input, the editing range “48-51”, and the editing type “collaboration”.
In addition, for example, the update information supplied from the terminal 21n to the server 23 includes the user ID “A002”, the file ID “0000540”, the view range “25-75”, the caret position “50, 10”, the data “Hel” being currently input, the editing range “48-51”, and the editing type “collaboration”.
In this case, the user information read out by the server 23 and the update information supplied from the terminal 21n to the server 23 are different from each other only in the caret position, and are the same in the other items.