OptionalcadenceOptionaldistanceDevice-recorded cumulative distance (m); present iff the source carried it (a GPS-less ride's distance axis).
OptionalhrPositions — present (length n) for a GPS activity, EMPTY for a GPS-less one
(the cols.lat.length hasTrack signal).
OptionalpowerOptionaltempAbsolute sample times in seconds (key column, ms → s).
The raw typed-array columns of an activity — the zero-copy read path the whole compute layer reads from.
lat/lngare present only for a GPS activity; the other channels are present iff the source recorded them (missing cells are NaN). Optional channels are absent from the object when the source had none.