Strictly speaking threshold braking, as the name suggests, is braking right up to the limit of adhesion without going beyond. Cadence braking is a pumping of the brake pedal in extreme conditions. The 'cadence' comes again from the meaning of it's name, in this case 'rhythm'. The idea is that for each press of the pedal, when the wheels lock the point of maximum braking must have occurred so you do that as many times as possible - which is exactly what a modern ABS system does.
Threshold, i.e. braking as hard as possible and then backing off a little and trying again if they press too hard is what most people do. Cadence, in it's proper form, is used very rarely only really in extreme circumstances where the wheels lock almost as soon as you brake at all.
I am not at all surprised that the names have become confused; and with no training in these techniques and modern electronics taking over, the skills themselves may well end up lost altogether. Shame.
-- Mark Foster, Brighton, Suslove, UK PGP Fingerprint: 3342 C02C 7BE8 3FE4 AAC5 8BB2 03B7 9263 DDF2 04C1 -------------------------------------------------- "There are no such useless words as...'I didn't have a chance.'" Driving, HMSO
