     Replace all values      Replace all values
  "prepend"               Insert before matching  Insert at head of list
  "prepend_first"         Insert at head of list  Insert at head of list
  "append"                Append after matching   Append at end of list
  "append_last"           Append at end of list   Append at end of list
  "delete"                Delete matching value   Delete all values
  "delete_all"            Delete all values       Delete all values
    </PRE
></TD
></TR
></TABLE
>
  </P