Mike,
I was simply saying that a paper certificate is simply an unneccessary complication, once there is a database of deacs available to the Police.
One could tamper with a deac even with a certificate well kept together with it.....
A sensible procedure would be, in case of a control, that the Police check if the weapon was legally deac, then, if doubts arise about it having been "reac" then have it inspected.
Andrea