US Patent 7831572 Maintaining and displaying user ordered lists

A system and method for updating a source copy of an ordered list (the source list) comprising a plurality of list items according to modifications made to the order of the list items in a local copy of the ordered list (the local list) is provided. Each list item includes an order value. The order of the list items is determined according to the order values. To update the source list, the list items that have been moved in the local list are identified and placed on a temporary list, retaining the ordinal position in the local list. For each list item in the temporary list, the list item is placed back in the local list and its order value is set according to the average of the previous list item's order value and the subsequent list item's order value. The list item is then written to the source list.