You are probably the first person to ask about this issue - congratulations
This system applies almost exclusively to alu frames (but not all).
As you can see from the old system the serial number P 0253 remains
But since 1996 a second serial number appeared - probably because the frames were produced outside Meise, somewhere in Italy.
This second number is the manufacturer's or order number. Until 2002 it looked like this, for example:
980013 where 98 is 1998 (year of production/order) and 0013 is the next frame from that year
From 2002 it looked like this:
U061813 where 06 is 2006 and 1813 is the next frame from that year
The dates of the second serial number precede those of the classic EMC serial number - this is quite logical.
Attention!
The two systems are not linked i.e:
An earlier frame from the second system may have a later number from the EMC system, e.g:
J6366 020069
J6843 020002
or
H9062 200252
H9537 200068
Your frame:
P0253 - indicates early 2007
U061813 - ~autumn 2006
43 - frame size
Some alu frames manufactured since 1996 do not have a second serial number
Some of them were built in Meise for profi teams
EMC alu designations are a galaxy closely watched by me but not yet explored