Ledge

From SmashWiki, the Super Smash Bros. wiki

A ledge (also known as an "edge") is any part of a stage from which one can hang or tether. Some stages have ledges in the middle of the stage, or none at all. On most neutral stages, however, there are two ledges, one on each end of the stage. The ledge, therefore, becomes an important factor in the battle between an edge-guarder and a recovering opponent. On certain stages (namely Norfair), there are passable platforms with ledges.

In Brawl's Stage Builder, only normal blocks can be "grabbed", and only if they are at least two units above a floor surface. Ice, Drop Blocks, slopes, and other objects can not be hung from.