3.49. OnFly
Enables on-the-fly item additions to the shopping cart. If set to the name of a valid UserTag, that tag definition will be used to parse and format the item with the following call:
$item = Vend::Parse::do_tag($Vend::Cfg->{OnFly}, $code, $quantity, $fly[$j], );
$fly[$j] is the value of mv_order_fly for that item. A default onfly tag is provided by Interchange. For more information, see the section that describes how to set up an on-the-fly item.