Title: Method of synchronising three or more electronic devices and a computer system for implementing that method
Patent application publication number: 20070033271
Publication date: February 8, 2007
Filing date: October 12, 2006 (priority to September 9, 2002)
Link to PDF: 
(26 pages)
AIPW Summary: You have to do a little digging into this application to find out that it’s an Apple case (see paragraph 0015). This application is about synching three or more devices. An original value for each item of information is stored. When one item is changed, that change is stored along with the original value and the changed value is replicated to the other devices. The changes are also retained in one of the devices, so that any other devices that had the original information can sync properly when that new device is present (paragraph 0047). Multiple changes can be compressed, in order to save memory space and synchronization time. An example given in the application shows a change from value x to value y, and then a change from value y to value z. This can be compressed to a change from value x to value z (see Figure 3 and paragraphs 0048-0049). The number of changes to track can be limited to avoid overloading during synchronization, and an indication that a larger chunk of information needs to be copied.
This application surprisingly has only one claim – albeit a very broad one.
Related case: 20040044920 (28 pages)