It's
  A - Must be crushed - Cannot normally be returned to the road
 B - May be broken for salvage - Cannot normally be returned to the road 
 C - Too expensive to repair commercially - Can be returned to the road
 D - Everything else (new for old etc) - Can be returned to the road 
 AB&C have markers against them set when the insurers pay out (DVLA notified using a V23)
 If you try to re-register it, the flag is noted and in all instances the relevant local police authority are notified. This is to protect against "ringing" 
 You then have to undergo a new vehicle test to inspect for the repairs, and also that the vehicle is not a ringer. 
 It's the Vehicle Identity Check scheme  
http://www.vosa.gov.uk/vosa/carlgvow...heckscheme.htm  So you could (possibly) put it back on the road, or break it or track it...... 
 Can't see why it's a B though. should have thought it would fall under Cat C if there's no structural damage.   
 [Edited on 12-4-2005 by Mr_S]