12-byte DLLs in winsxs with a magic of 'DC'

I have observed that there are a number of 12-byte DLLs in various sub-directories under \windows\winsxs. The first two bytes contain ‘DC’ in what would be the magic of a DOS header. The remaining bytes don’t appear to represent the ten bytes succeeding the e_magic field of a DOS header. (Not a surprise.)

I know that this is something special with side-by-side but I haven’t found any information on these DLLs. I’m assuming that the twelve bytes are used to identify them to s-x-s in an undocumented manner.

I am just curious what they are and what they represent. I am reviewing replication of system files and, at first, I thought they had been truncated but now I see they aren’t.


Never noticed those before and I’m not finding anything useful either. In
case it helps with your searching, poking around I also see non-12 byte
files that start with 44 43 53 (“DCS”) and 44 43 44 (“DCD”).


Thanks Scott, a couple more pieces to the puzzle.