a copy of this feed with the specified items appended to its items
a copy of this feed with the specified items prepended to its items
a copy of this feed with the specified items removed from its items
a copy of this feed with all items removed
a copy of this feed with its items replaced by the specified ones
a copy of this feed with its items in reversed order
a function that defines the order of two items (is the first one before the other?)
a copy of this feed with its items in sorted order
It is implementation dependent, how items without date or items with multiple dates are sorted in.
It is implementation dependent, how items without date or items with multiple dates are sorted in.