A Railstand is when one edge of your board is on the ground and you are standing on the other, usually with your feet also on the wheels. From this position you can do many tricks, including flips, 180s, 360 Spins and combinations of the above (landing into another railstand if you wish), landing into casper, into 50/50 / Truckstand etc. A Heelside Railstand is to stand on the board in railstand, with your griptape facing your back, and Toeside is the reverse. There are several ways to get into Heelside Railstand as opposed to the limited ways, if not just one way of getting into Toeside Railstand. A common variation of a railstand is a cooper stand, which is a rail stand with one foot on a wheel, and the other on the nose. While in Railstand, the limit to what you can do is almost non existent. You do not have to just flip. You can varial the board under you so it spins without flipping, you can stand on one wheel, on one foot and kick the board forwards or backwards so it spins around the one wheel.
This is a Railstand but done while moving, so you slide along the ground on the side of your board. Named for its inventor, [Primo Desiderio]. For added style you can turn the board 90 degrees while sliding doing sort of a Primo Power Slide from there you can do any trick you want to get out of it, flips, spins etc.