Schema for describing and exploiting Solar Resource Knowledge. Units are expressed as string. Examples: kWh/m2, W/(m2.sr), W.m-2.sr-1, rad, degree. Latitude and longitude are expressed in decimal degrees. Elevation is in meters. Describes a single observation. Date is the end of the interval of observation, value is the count (measure), uncertainty denotes uncertainty and reliability denotes the confidence in the observation. Note that the interval of measurement is not defined there. For example, if the period is 1 h, dateTime equals to 2008-25-01T18:43:26 means that the observation was made during this day from 17:43:27 to 18:43:26. If the interval of observation spans over several years, e.g., 10, for a given month, date will be equal to e.g., 2002-01 for the month of January, with measurements between 1993 and 2002. Describes a series of single observations. ObservationType can be found in a dictionnary, e.g. URL. Note that usually date denotes the end of the period of the measurement (duration). For example, if the period is 1 h, dateTime equals to 2008-25-01T18:43:26 means that the observation was made during this day from 17:43:27 to 18:43:26. It happens that several observers do not follow that rule and that the time may be, say the middle of the hour. The "offsetInstant" has been created to manage such case. It is expressed in percent. 100 means that it is the end of the duration, 50 the middle, 0 the beginning etc. Duration is defined as ISO8601 duration, form: PnYnMnDTnHnMnS. Example: P1M is a one month duration, P10Y is a ten years duration.