South-east rule

The south-west rule is a likely unintentional mechanic in Minecraft where various effects naturally "point" in some directions more than other directions, or otherwise act differently depending on the direction.

As the player's spawn faces to the east (where the sun rises), so do the "top" of blocks, as their origin is apparently in the upper-right corner (if east is the top, then the northeastern corner). This has many effects in the game:
 * When placing minecart tracks, they will favor linking to their north or east edges.
 * Minecarts will favor south or west motion at a "T" due to the fact they favor "starting" at the north or east edge.
 * The north and east faces of a block on fire will burn a player who touches those sides, while the south and west sides do not.
 * The northeast corner of a block that has blocks to the north and east of it will effect its properties to a block (or player) touching that northeast corner. All other corners are "safe" since they have a south and/or west edge buffer.
 * A player, boat, or mob touching the northeast corner of a water block can swim even if blocked on the south and west sides.