For those who are interested, I've found something interesting in the German Ubisoft Forums.
"The 4GB patch is at a 32-bit executable in the file header, the bit-Falg ensures that this exe also address memory addresses above the 2GB limit.
The patch works so that it negates the bit is from 0 to 1, is from 1 to 0 1 means the exe can not address more than 2GB, 0 means they can only max. 2G address.
Now, the Romanian Ubisoft Developer and thought along the same SH5.exe with active bitflag compiles*so this game of home address more than 2GB can.
If now the 4GB ironed over it, then from the 1 is a 0, and then for the exe is end of the shaft *at 2GB."
It's translated with google and i Think it sounds logic.
Kalle