Difference between couplers and docking ports (When docking assemblies)

[I_do_robots]

Probably been addressed before so (Unanswered) is presumed of course...

If I have a large assembly, regardless of whether the end coupling and the mating coupling on the main body of a given platform are the same, can those be mated / coupled the same as docking ports work?

I suppose I can replace the couplings with Docking port Sr. on all the mating points of the assemblies instead and just avoid the guesswork.

If that is the case, can a standard docking port (Like my tug has.) or one of the covered (Shielded?) docking ports, either one, mate with a docking port Sr., despite the size difference?

Thank you for your assistance.

Edited September 9, 2013 by I_do_robots
Answered

[Evrion]

If you are building the whole thing in the Vehicle assembly building, it doesn't really matter so long as KSP accepts them, they will work.

If you are putting it together after launch, you MUST use docking ports of the same size.

[M4ck]

Or use this, I've created it several hours ago. You just need to paste the code into any part.cfg file after the last "}" of an existing part(or make a new one), it doesn't require installing anything else. Just try not to mate two of these ports to each other, it can go a bit messy.

[KerbMav]

You may have created one of the more useful parts for my space shipyard.