They can be registered online. With my ResQFix i can go online and update the details or the adventure I'm having each time I leave. If you have any health issues etc that can all be added. Keeping the registration up to date is quite important. I update mine each time to say how many are on my boat, what stuff I have brought with me, who my safety contact ashore is etc. If anything should ever happen, they have some good info right at the get go.
There is a tide in the affairs of men,
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
Shakespeare, Julius Caesar IV, iii, 217