>>999 replies to post number 999, if it exists on this board.
>>z1y2x3w4.999 replies to post number 999 on the board with tag z1y2x3w4. Click the post's number to automatically type this.
>>z1y2x3w4 cross-posts the thread to the board with tag z1y2x3w4.
If you check the "Merge/Leech" box, the thread will continuously include all posts from up to 5 threads referenced in the OP.
[spoiler]Spoiler tags work like this.[/spoiler]