Once BDD.EXCHANGE is purchased by a user, the Issuer will buy back the EXCH share(s)
[...]
Users may also decide to hold the BDD.EXCHANGE share
How?
Either you automatically exchange them via buyback, or you allow users to hold it... I'm not sure how it would be possible to do both...
Normally, the exchange will normally be processed much quicker than 24 hours.
Small typo.