<character> (tab, Control-I, HT, ASCII 9) A character which
when displayed or printed causes the following character to be
placed at the next "tabstop" - the column whose number is a
multiple of the current tab width. Commonly (especially in
Unix(?)) the tab width is eight, so, counting from the left
margin (column zero), the tab stops are at columns 8, 16, 24,
up to the width of the screen or page.
A tab width of four or two is often preferred when indenting
program source code to conserve indentation.
