Start date of aggregation

Each measurement is taken to represent an interval of duration equal to the sampling interval (In this data set, the sampling interval is 10 seconds). This attribute represents the date of the beginning of the interval represented by the first measurement in the aggregation.

ATTRIBUTE-ACCURACY

Times are derived from the volunteers watch, and are considered to be accurate within a couple of minutes.

DOMAIN

A positive integer presented as YYYYMMDD, where YYYY represents the year, MM represents the month within the year, and DD represents the day within the month.