19. The computer-implemented method of claim 16 , wherein determining that the content item has previously been stored as a second change with respect to the previous version comprises comparing the previous version identifier with a version indicator stored in association with the content item.
16. A computer-implemented method comprising: receiving, from an application executing on a first client device, a notification of a change to a content item stored on the first client device, the notification of the change including: a numerical indication of a first record of the content item and a numerical indication of a first field within the first record in which the change was located, and an indication of a previous version of the content item identified with a previous version identifier; determining that the content item has previously been stored as a second change with respect to the previous version, the second change specified as being located within a second record of the content item and a second field within the second record and resulting in a second version later than the previous version; providing, to the application executing on the first client device: an indication of the second record and the second field, and an identifier of the second version; receiving a request from the second client device to receive changes to the content item; registering the second client device to receive changes to the content item; receiving, from the application executing on the first client device, an updated notification of the change to the content item stored on the first client device, the updated notification including: an indication of the first record of the content item, an indication of a merged change resulting from the application executing on the first client device merging the change with the second change within the content item stored on the first client device; responsive to receiving the notification of the merged change, providing a notification of the merged change to the second client device; and storing the content item as the indication of the merged change in association with an identifier of a resulting third version later than the second version.