Discovered by Savestate, Dimensional Arrow is a sub-glitch of Chain dance in versions 1.00 and 1.01 of Super Smash Bros. Melee that allows Link and Young Link to release an arrow from behind themselves.
Dimensional Arrow is performed by throwing a boomerang, and then timing the boomerang to return to Link right after wall-grappling on a wall or the side of a stage with flat walls. Once Link/Young Link enters their boomerang catching animation, B-reverse, and the player will see Link/Young Link begin to charge their bow while they are still hanging on the chain with their back to the wall.
When performed correctly, the game will try to push Link backwards but is unable to due to the wall, and will continuously add velocity, attempting to correct the misalignment. This pushes his projected ECB (based on velocity) further and further back each frame. Coincidentally, Link and Young Link's arrow is released from the position of the projected ECB, allowing them to release an arrow far behind them.
The game determines whether or not a player has crossed the Blast zone by using their projected ECB. Due to this, Link can die off the side of the stage by charging his bow long enough for his projected ECB to reach the blast zone.