ECCM and ECM, normal vs compact vs small craft

[jseah (OP)]

While research ECCM, I noticed compact ECCM. 

Currently, I am at ECCM 3, awaiting ECCM 4 advance from data handed to me by wrecks. 

After researching compact ECCM2, I noticed that compact ECCM 3 doesn't exist to be researched. 
I thought this might be because ECCM 4 isn't unlocked but looking at all projects doesn't seem to be the case.  ECCM 10 is the maximum level but compact ECCM 10 is also the maximum level. 

How then are we to reach compact ECCM 10 (which is roughly possible for me if I max out my research in it for ~30 to 40 years)

[Ziusudra]

I thought this might be because ECCM 4 isn't unlocked

I'm pretty sure that that is the case. I know compact ECCM 1 isn't available until ECCM 2 has been researched.

Edit: I just checked with instant on a new sandbox game and this is it. The compact ECCM 3 requires ECCM 4. Each level of compact requires the previous compact and the next non-compact. Except for compact 10 which only requires compact 9.

[Brian Neumann]

The normal progression is you need the full size ecm/eccm before you can research the previous level of compact.  For small craft ecm/eccm the level you can researchis 1/2 the compact ecm/eccm round down.  So small craft ecm 2 needs compact ecm 4, and small craft ecm 3 would require compact ecm 6 which would itself require the full size ecm 7.  The only exeption to this is for the compact ecm/eccm 10 which as he said only needs the level 9 compact researched first.

Brian