🚀 go-pugleaf

dvips.tex says:

    \o-e num:
    Make sure that each character is placed at most this many pixels from its
    `true' resolution-independent
    position on the page. The default value of this parameter
    is resolution dependent (it is the number
    of entries in the list [100, 200, 300, 400, 500, 600, 800, 1000, 1200, 1600,
    2000, 2400, 2800, 3200, $\ldots\,$] that are less than or equal to the
    \^{maxdrift}
    resolution in dots per inch). Allowing individual
    characters to `drift' from their correctly rounded positions
    by a few pixels, while regaining the true position at the beginning of
    each new word, improves the spacing of letters in words.

what on earth is this for?  what kind of `drifting' is it, and how
does it improve the spacing of letters in words? 

	-ian