This is a COMBO CABLE/ COAX/#18 AWG PAIR
This is "Technically"
known as "Siamese" or "Siamese Cable".
Installed apx. 100,000 KM of the stuff!
The PVC (CMR, Riser, etc.) type Jacketed Cable has a larger O.D. than the Plenum (CMP) type Jacketed Cable.
Also, the Plenum Rated stuff pulls through Conduits better, but costs 2× - 3× the $$$ of PVC (Riser) Cable.
Cable Manufacturers will have the O.D. displayed on their web sites.
BTW, thanks for the links! Will check 'em out.