CAP670 states radar recordings must be captured 'through the wall' and 'at the glass' so it is recorded in the form it arrives to a tower or centre from the radar site, it is also recorded from the display that the controller can see. CAP670 states it should be stored for 30 days I believe.
The through the wall data is pretty raw but most recorders now have a very simple inbuilt RDP (radar data processor) to make sense of the raw radar feed.
MLAT can also be recorded through the wall or at the glass.
Yours,
tels