What exactly is a foundation bred shetland?

[LostandFound]

If your horse has a yellow stamp looking thing on his papers that is supposed to be foundation bred, but what exactly does that mean? Do they have to do anything or prove anything to get it?

 

[chandab]

I'm not sure I fully understand it, but IIRC it's bloodline, they have to be connected to foundation Shetland lines with no outside influence (Hackney was introduced to American Shetlands at one time, giving the Modern type). I'm sure there is more to it, but this is all I've retained.

 

[Minimor]

To be Foundation sealed a pony has to have 4 generations of A papered ponies. If there is a B papered pony in the first 4 generations then the pony cannot be sealed.

 

[LostandFound]

What is an A or B papered pony?