HELP ON                                                     A. Sloman, April 85

ON is used in one form of the FOR statement, viz:

    for <variable> on <expression> do <actions> endfor

This evaluates the expression, which should yield a list, and then performs
<actions> with the variable set first to the list, then the TL of the list,
then the TL of the TL of the list etc. For example:

    for x on [a b c] do x => endfor;
    ** [a b c]
    ** [b c]
    ** [c]

See HELP
    *FOR   - forms and uses of FOR loops in iteration over lists and integers
    *LOOPS - for other types of iteration