Quick answer
WXF reference · Article 19
Check
A move attacking the opposing King so it could be captured next move. A mating threat need not attack the King immediately.
According to WXF 2018 · Article 19.1. Diagram 1.
Mating threat · Kill / Mating threat
A preparatory move threatening a check or checking sequence ending in mate. Positional pressure alone is insufficient.
According to WXF 2018 · Article 19.2. Diagram 7.
Chase
A move threatening to capture a non-King piece next move. One chase alone does not establish a perpetual chase.
According to WXF 2018 · Article 19.3. Diagram 33.
Exchange
A move or sequence trading one's piece or combination for opposing material. A move also classified as chase needs 20.8.
According to WXF 2018 · Article 19.4. Diagram 107.
Block
Preventing an opposing piece from advancing, retreating or traversing without threatening to capture the blocked piece.
According to WXF 2018 · Article 19.5. Diagram 8.
Offer
A move inviting the opponent to capture the piece just moved. Do not assume an offered piece makes all other attacks idle.
According to WXF 2018 · Article 19.6. Diagram 107.
Idle
A move that is not check, mating threat, chase, exchange, block or offer. It is a technical classification, not an assessment of quality.
According to WXF 2018 · Article 19.7. Diagram 107.
Perpetual check · Perpetual Check
Checking on every move in a sequence causing threefold repetition. The checking piece need not remain the same.
According to WXF 2018 · Article 19.8. Diagram 1.
Perpetual mating threat · Perpetual Mating Threat
Repeating mating threats on each own move. Check for another simultaneous nature before applying 20.2.
According to WXF 2018 · Article 19.9. Diagram 7.
Perpetual chase · Perpetual Chase
Successive chases against the same piece, answered by moving it away or resolving the chase with another piece. Target identity and replies matter.
According to WXF 2018 · Article 19.10. Diagram 33.
Resolve-kill
A move directly defeating the opposing mating threat. Resolve-check and resolve-chase use the same idea for their respective threats.
According to WXF 2018 · Article 19.11. Diagram 8.
Cross-check
Resolving a check while checking the opposing King. Merely checking on the next turn is not enough for this label.
According to WXF 2018 · Article 19.12. Diagram 4.
Protected piece / root · Protected piece / Root
A piece is protected if a friendly piece can recapture the enemy that takes it; that protector is its root. Otherwise it is unprotected.
According to WXF 2018 · Article 19.13. Diagram 29.
Real root · Real Root
The protector can immediately recapture after the target is taken. The recapture must be legal, including King safety.
According to WXF 2018 · Article 19.14. Diagram 30.
Fake root · Fake Root
The apparent protector cannot move to make that recapture. A pinned protector may therefore be a fake root.
According to WXF 2018 · Article 19.15. Diagram 83.
Alternate check and mating threat · Alternate Check and Mating Threat
Repeatedly alternating a check with a mating threat. Similar names classify check/chase and other mixed sequences.
According to WXF 2018 · Article 19.16. Diagram 11.
Two-to-one check · Two-to-one Check
One player checks perpetually; the opponent counter-checks on every other response. It does not mean two equal perpetual checkers.
According to WXF 2018 · Article 19.17. Diagram 5.
Two-to-one chase · Two-to-one Chase
One player chases perpetually; the opponent counter-chases on alternate responses. Read the target and the full cycle.
According to WXF 2018 · Article 19.18. Diagram 82.
Two-to-two chase · Two-to-two Chase
A player makes consecutive chases and the opponent answers with a chase on each move. Examine the applicable bilateral case before ruling.
According to WXF 2018 · Article 19.19. Diagram 108.
Read the definitions together
Check concerns the King; Chase concerns another piece. Root concerns an immediate recapture, and Fake Root concerns why that apparent recapture is unavailable. Article 19.10 also includes the opponent's response: moving the target away or resolving the chase with another piece.
Diagram 4
Diagram 30
Diagram 83
FAQ
Can a move have more than one nature?
Yes. Chapter 5 §36.4 treats Diagram 109's mating threats as chases because that classification has the more substantial consequences in the example. Do not select whichever label gives the player a preferable ruling.
Related topics
Source and scope
According to World XiangQi Rules · World Xiangqi Federation · 2018. Article 19.
These guides explain the WXF 2018 rules. They do not replace the official rules or the regulations of your event.