Not by the comma, exactly. It's called a "decimal tab," and it aligns
figures on the decimal point or the position assumed to represent it. As a
practical matter, it aligns on the first non-numeric character (other than a
comma) following a series of numbers, so it works fine with parentheses,
asterisks and other footnote reference marks, etc. If you're using tabbed
columns, you set the decimal tab stop and tab to it; in a table, you just
set the stop (making sure that your text is left-aligned), and the text will
jump to it automatically.
