Default DRM Explonation

Since a long time I'm wondering about connections between some EXT packages and how important they are (if they are).

DRMMiddleware_1_5_19122329_00
LockStreamDRM_1_2_081216_O9_02
DiscretixDRM_1_0_20090422_00
mHubVO_1_75_090515_X0
DRM (SYS folder)

and now... are they all neccesary or I can remove some of them? I've also heard that there is connection between numbers like DRMMiddleware_1_5_19122329_00 is working with mHubVO_1_75_090515_X0 but with mHubVO_1_73_090424_X0 no.

And another thing... why in mHubVO_1_73_090424_X0 there are 23 files and in newer version mHubVO_1_75_090515_X0 only 2 files?

Can someone make it clear please?

THANKS!