(1) The sequence in which the characters are ordered for the purpose of sorting, merging, comparing, and processing indexed data sequentially.
(2) An ordering assigned to a set of items, such that any two sets in that assigned order can be collated.
(3) A specified arrangement used in sequencing. See also collating element.
(4) The relative ordering of collating elements as determined by the setting of the LC_COLLATE category in the current locale. The character order, as defined for the LC_COLLATE category in the current locale, defines the relative order of all collating elements, such that each element occupies a unique position in the order.