Franck
All I can say is that Skz blocks were not always complete A-Z. there were often breaks and missing letters for one reason or another.
There are typo or sounding errors in the records of course as well.
The Finnish records are there. It help with the movements of Bf109E-7 3579, Bf109 3523 and Fw189 2100 through Finland. All were lost in the North and subsequently recovered.
Here is another thread relating to movements to the north - both recorded by tactical number, W.Nr or Skz.
Kari had access to the archives and has been extremely helpful over the years.
http://forum.12oclockhigh.net/showthread.php?t=16019
regards
Mark