What is the cannon called in Chinese — 炮 or 砲?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
Both, and both are correct. 砲 carries the stone radical 石, from the trebuchet-style engines that threw rocks; 炮 carries the fire radical 火, from gunpowder artillery. Which side gets which varies between manufacturers and books, and nothing about play depends on it.
A small piece of history in the character
The older weapon threw stones, and the older character reflects it. The gunpowder cannon came later, and so did 炮. That the piece exists at all is itself a dating clue: the cannon appears in xiangqi around the Song dynasty, which is when artillery became familiar in China.
In notation
Chinese records use whichever character the set uses, and WXF romanisation sidesteps the question entirely with C. So 炮二平五 and 砲二平五 are the same move, written C2=5 either way.
Related questions
Which one is Red's?
It varies by set and by publisher. There is no universal convention, unlike 帥/將.
How is it pronounced?
pào, for both characters.
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