is there any reason why anyone needs a photocopy of it?
To prove you have it probably, did they copy your licence?.
i have been asked to bring my licence and digitach in to the office within 28 days. i assume its for copying. to do with the working time regs apparently 
they have a copy of my new licence though. i gave them a copy as soon as i got it back from DVLA and i dont see why they need anything from my digitach. its my card and to my knowledge, there is absolutely no reason for it to be copied by or for anyone else
…and to show the reference number and expiry date.
That shows the authorities that they have physically seen the card, and not just taken the drivers word that he has a valid one at the time.
The same as Jammy said about your licence: a decent employer will ask to see, and then photocopy, write on the date, and then file, the copy of the paper part of your licence - every three months.
This is in case a driver ‘forgets’ 
to mention to the boss any endorsements and penalty points he may have been recently awarded (which may lead to Insurance problems, should he (or she…) then be involved in a bump or something. 
)
scanny77:
its my card…
Technically it isn’t. Just like your driving licence your digi card belongs to the Secretary of State for Transport. On a couple of occasions I have heard drivers claiming that it against the data protection act/human rights act/their civil liberties to download the info from their card and if anyone wants to they will tell them they can’t. Kinda takes the wind out of their sails when you point out the card doesn’t actually belong to them. 