How does the C3D file format store 3D points and analog channels, and how must scale, rate and units be handled?

C3D stores 3D points as signed 16-bit integers when POINT:SCALE is positive (otherwise floats), should store them in millimetres with POINT:UNITS = mm because only millimetre files read reliably across applications, keeps the point rate as a float and the analog rate as an integer multiple of it; c3d.org describes C3D as a public-domain format. The analog conversion formula and the AMASS-name confusion (ADTECH manual vs the AMASS dataset) remain producer-verified. Curator qualifications: Guide verified from producer copy; no C3D file parsed. Guide verified from producer copy (hash equals pin), not a curator readback. Analog scaling formula and ADTECH AMASS manual per producer. Limitations: Guide verified from producer copy; no C3D file parsed. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

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