What is a "Low Moose" tree in a saddle

[3 Bay Ranch]

I have been looking at saddles and trying to determine what different tree styles are. What the heck is a low moose saddle?

[rsandi5218]

http://www.ranchworldads.com/classified.php?listing=7968

[3 Bay Ranch]

I have seen ads for a 'low moose' saddle - but I don't see why it is calle that. Do you know?
I'll call a saddle maker in the next few days..just hate asking dumb questions...