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looking for a file format for time series data other software can easily consume

I plan to produce some time series data and i would like it to be in a
form that makes it easy or effortless for pre-existing programs to
plot or even process further.

The data would consist of a few hundred to a few thousand time points,
and for each time point there would be a half-dozen to a dozen values.

So conceptually it would be something like a csv file with a few
hundred to a few thousand rows, and a half-dozen to a dozen columns.

However, a csv file doesn't seem exactly right, as i would like the
files to include some embedded metadata (ideally in some form that at
least in principle could be digested by another program).  I suppose i
could have some comment lines somehow, but that feels pretty ad hoc.
But maybe i'm being overly fastidious.

Something like a RIFF file format (like WAVE) might be better, but not
sure what it would be.

For the plotting or processing software i'd want to use something like
octave or python/matplotlib or a derivative.

I googled around for time series file formats, and i didn't see
exactly what i was looking for.

So i'd appreciate any advice or suggestions, and thanks in advance!