More likely it's a @window opened with the -t switch.
  • The -t switch used to set the tab positions in a listbox.

    t[N,...,N] = specifies the tab positions in a listbox, if text contains tabs it will be
    spaced out according to these tab settings

You then use a tab ($chr(9)) to seperate the columns.
e.g.
Code:
//window -l -t10,20,30,40 @window | aline @window row1	two	three	four | aline @window row2	text	more	data