A while back, I posted that G12 coolant was made by Pentosin.
Just a correction for the record - it appears that G12 is actually made by Valvoline (Zerex), although Pentosin makes a similar, and I believe compatible, coolant.
G12 is Valvoline/Zerex Glysantin G 30, the datasheet for which may be found at http://www.valvoline-technology.com/
It was developed in conjunction with BASF, and more info on G12 is to be found at http://www.basf.de/en/produkte/chemikalien/spezial/glysantin/specification/
The VAG specification for G12 antifreeze is TL 774-D.
In January, 2003, VW/Audi introduced G12+ (part number G 012 A8F A4), an antifreeze with purple coloration. It can be freely mixed with the original pink G12 (part number ZVW 237 G12). The VAG specification for G12+ is TL 774-F. From the information at the above BASF site, Glysantin G 30 meets both specifications. I believe that the only significant difference between the two is the color - changed to help prevent people from thinking that GM Dexcool compatible (typically orange) coolant could be used to top-up the original G12 (pink), which is not the case.
The older, blue-green, VW G11 coolant has VAG specification TL 774-C, and is Glysantin G 48.