What is Fluid Grid ASCII file format?

What is Fluid Grid ASCII file format and how to use it? Who is author of this format and where I can find official documentation?
I want to build my own particle system with my own vector field authoring tools.

I know it’s an old question but for anyone stumbling upon it like I just did, here’s a link to related discussion on UE4 AnswerHub.

Essentialy it is a simple ASCII file with the following structure

10.0, 10.0, 10.0,       # Cell count in X, Y and Z axis
-100.0, -100.0, -100.0, # Bounding box minimum X Y Z
100.0, 100.0, 100.0,    # Bounding box maximum X Y Z
0.0, 0.0, 0.0,          # Velocity vector in the first cell
0.0, 0.0, 0.0,          # Velocity vector in the second cell
...
0.0, 0.0, 0.0,          # Velocity vector in the last cell

The numbers can all be just packed together in a single line. And I usually see trailing comma character at the end of the file but I’m not sure if it’s required.