For mergeability, it's generally easier to manage having the items on lines by themselves (sorted if possible).  The idea being, if two people add an item to a single line, it's more difficult for the patch processor to decide where the item should go (even worse if more than one person is adding more than one item, especially if they're unordered)... if the list is sorted (if possible) and on individual lines, the patch process can make more intelligent decisions.