>>187
CSC is the Country/Carrier Specific Code
(not sure exactly which it is, both kinda make sense). It contains the files for customisation for specific networks, so will have the
APN settings, maybe custom ringtones or backgrounds,
and can have programs too.
Some CSC files contain a lot more than others, hence
the file size differences.

コピペですまん

CSC焼くとdocomoの回線が使えなくなるかもしれないってこと