If Black shifts the King left on the first move, Red could continue with R2=4, followed by K5=4 and win.
Think of how to force a lethal pin with the Cannon before you make the first move.
Most xiangqi books call this “Piercing the Heart” (大胆穿心) checkmate. However, the term is more appropriate for describing a tactical process. It is the sacrifice of a Pawn or a Chariot at the palace centre (B51 or R51) to kick start an overwhelming attack. It could end with different checkmate formats.
Red offered his 7th file Chariot twice: first to destroy the Horse guarding the B40 spot; then to restore the Cannon pin that was thwarted by the enemy Chariot.
In real games, the “Iron Bolt” may sometimes disguise itself in rotated formation. Below are two examples. You will recognise them easily if you view the position from the side of the board.
R2=4 checkmate
R5+5 checkmate. Compared with the usual vertical format, the Black King has an escape door if the Red King is not controlling the 6th file. I do not classify this checkmate under the Royal Checkmate, which term I use only when no other ally piece is sharing the credit of interception.