Description of File-Format for "HRV Measures - .CSV Import" function
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Example file:

timestamp_measurement,HR,AVNN,SDNN,rMSSD,pNN50,LF,HF,HRV4T_Recovery_Points
2017-04-01 09:56:21 +0000,43.92,1364.75,84.05,67.54,40.48,0.0418,0.0339,8.37
2017-04-02 09:27:24 +0000,43.42,1348,59.46,56.38,32.56,0.0655,0.0331,8.09
2017-04-03 07:37:03 +0000,41.38,1502.73,76.92,72.04,60.53,0.0476,0.0516,8.47

this was generated by HRV4Training App with unsupported columns and empty lines removed using a spreasheet.

a) Header Line
First Line of a valid file has to contain header information. This has to be a comma-separated 
list of the measures provided in the data lines. You do not need to provide all possible measures,
but at least "timestamp_measure" and "rMSSD".

As mandatory field you need time/date of the measures:
- "timestamp_measure" - ISO8601 formatted Date/Time String

The mandatory measure is:
- "rMSSD" - Square root of the mean of the squares of differences between adjacent NN intervals

The optional measures are:
- "HR" - Average HR
- "AVNN" - Average of all NN interval
- "SDNN" - Standard deviation of all NN intervals
- "pNN50" - Percentage of differences between adjacent NN intervals that are greater than 50 ms
- "LF" - Power at Low Frequencies
- "HF" - Power at High Frequencies
- "HRV4T_Recovery_Points" - A log transform of rMSSD

Data formats:
- "date"	is a ISO8601 formated date/time 
- all other measures are float/double in format <xxxxxxx.yyy> 

There are very strict format checks when importing. Only if the whole
file is correct the data is imported. Any error (even in a single entry)
will block the complete import.

The following error will stop the import.
- Unknown measures in header
- Number of measures in header is different to number in an item
- Item measure in wrong format
- "timestamp_measure" or "rMSSD" is missing


