Can a pinned piece still act as a cannon's screen?
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
Yes. Being pinned only takes away a piece's ability to move; it does nothing to whether it can still serve as a screen, which is purely a matter of standing on the right point. A piece frozen by the flying general rule, or pinned against a chariot behind it, screens a cannon exactly as well as any other piece would.
Why this makes sense once you separate the two roles
A screen's job has nothing to do with mobility, it is simply about occupying a specific point on a line. A pinned piece is, if anything, an unusually reliable screen, because it cannot be moved away by its own side even when doing so would help them.
Where this comes up in practice
A piece frozen between the two generals is a common case: it cannot move for any reason, but a cannon behind it on the same file still fires straight through it exactly as if it were free. The pin restricts the piece's owner, not the cannon using it.
Related questions
Does the pinned piece's owner benefit from this at all?
No, the screen works the same regardless of whose piece it is or whether that side wants it there.
Can a pinned piece be captured while acting as a screen?
Yes, exactly like any other piece, being pinned does not protect it from capture.
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