Topside is a variation on soul based tricks done in the sport of Aggressive Inline Skating.
When a normal soul based trick is done in Aggressive Skating the soul plates of the skate are resting/grinding on top of the object. So if viewed from the end on, the skater would appear like they were standing on the object, with the feet positioned vertically. Click here to view a photo of Jenna Downing doing a normal Makio (not topside).
When a trick is done 'topside', the foot doing the soul based grind would not have the soul plates on top of the object, but the frames instead. This makes the grind harder and can be used to overcome the problem of skating objects on different sides. Click here to view a photo of a skater doing a 'topside soul'.
The variation 'topside' can be used in any soul based trick. Examples include; 'Topside Soul (often simply called a topsoul), Topside Mizou (AKA sweatstance) and the Topside Torque Soul.