What is the 110-diagram repetition casebook?
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
It is the official collection of worked repetition positions used to decide how perpetual check and perpetual chase cases are ruled. The repetition laws cannot be stated compactly enough to cover every position, so the casebook supplies adjudicated examples — and it is the reference this site's engine is regression-tested against.
Why a casebook rather than a rule
Because the interesting cases are combinations. One side checks while the other chases; a chased piece is protected; two pieces are chased alternately. A short rule cannot resolve these without ambiguity, so the federation published decided examples instead — the same approach a legal system takes for the same reason.
Why it matters here
Most descriptions of xiangqi online either omit the repetition rules or state a simplified version that is wrong in the cases that actually arise. Testing an engine against the casebook is the difference between implementing the rule and implementing a summary of it.
Related questions
Do online servers follow it?
Many implement a simplified repetition rule. This site's engine follows the casebook.
Do I need to know all 110?
No. Knowing that perpetual check loses, and that chasing is also adjudicated, covers everything a club player meets.
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