A list is a special kind of ObjectScript string, made up of a list of items. Although they are similar to delimited strings using $Piece, you work with lists using list-specific functions.
$ListBuild returns a list built from items. Concatenating lists creates a new list.
$List returns a specific item in the list. You can use an asterisk (*) to represent the last item, and *-n to count items backwards from the end.
$ListLength returns the number of items in the list.
$ListFind searches the list for an item, and returns its item number.
USER>set addr = "One Memorial Drive", city = "Cambridge"
USER>set st = "MA", zip = "02142"
USER>set mail = $listbuild(addr, city, st, zip)
USER>write $list(mail, 2)
USER>write $list(mail, *-1)
USER>write $listfind(mail, "MA")
USER>set office = $listbuild("InterSystems", "USA") _ mail
USER>write $listfind(office, "MA")
You can't use a list function on a non-list string, or you'll get a <LIST> error. Likewise, you usually will not use string functions on a list. Note that the abbreviations for list functions are two or three letters.