A low ramp-y oxer would be a jump at any low height, under about 3' (.95m I think) that is build with one side of the oxer higher than the other. So rather than building an oxer with the two top rails parallel (a 'square' oxer), you'll make sure one rail is at least one hole higher than the other. The higher rail will always be the back of the jump, you never want to jump a ramped oxer 'backwards', meaning jump the higher side first.
If you're thinking about turning your toe out more when you ride, do be careful that you don't turn it out too much. If you imagine that your horse's side is one line of an angle, and your foot is the other line, you want the point where heel and horse meet to be no great than 45 degrees. If I can figure out how to post pictures, I'll add some illustrations of what I mean by an auto/crest release and a ramp-y oxer. :)