sdd:rebinds
sdd:rebinds rebinds a sdd:Section's subject through a SPARQL property path, changing what the section's own sdd:Datum instances bind relative to (design spec §1, §2). A section written middle = plant:hasMotor acts as an implicit anchor: the fact chain P101 –hasMotor→ _:m mints one shared blank node for that section, and every datum nested inside binds section-relative — its own sdd:binds path resolves against _:m, not against the node's depicted resource.
This is deliberately the same sharing rule a declared sdd:anchor gets, and for the same reason: a fresh blank node per datum would break co-reference, the whole point of rebinding a section rather than repeating the same path on every datum inside it.