Clearing the screen and other such things.

[Guy Steele <gls@THINK-AQUINAS.ARPA>]

    Date: Sat, 27 Jul 85 05:11:22 EDT
    From: Tim McNerney <TIM@MIT-MC.ARPA>

    ...

     ERASE-CHAR-BACKWARD, ERASE-CHAR-FORWARD

    Many terminals don't support these operations.  If we are trying to limit
    ourselves to a set of essential primitives, I would suggest that these be
    flushed, since they are merely abstractions for printing the sequences,
    backspace-space-backspace and space-backspace, respectively.

	    Tim McNerney

    ...

This remark raises the question of whether the terminal has overstrike
capabilities or not; and if it does not, whether space is transparent
or replacing.

--Guy