CPT Date Formats
CPT uses the ISO8601 format standards for indicating dates. This format has the flexibility to represent points in time as well as periods. In the format the year is listed first, followed, optionally, by the month, and then the day of the month (again optionally). The year month and day are separated by dashes and must be printed as two digits with a leading 0 if needed. For example, 30 September 2009 would be indicated as 2009-09-30. If the day is missing, it is implied that the data are representative of the whole month (either as an average or an accumulation). For example, if the file contains monthly rainfall data for September, the days would be omitted in the date format, and September 2009 would be indicated as 2009-09. If the month were to be omitted, the year is then listed on its own, and CPT would interpret the data as representative of the whole year. (Note that in version 9 files where the month is unspecified CPT will assume that the month is undefined rather than that the data represent the whole year.) If the data represent seasonal averages, for example, it is possible to indicate the season in the date format by using a "/" separator for the start and end dates. For example, a July - September 2009 3-month average would be represented by 2009-07/2009-09. However, since the year is the same in both cases, this format can be abbreviated to 2009-07/09. It is implicit that the data are from 01 July 2009 to 30 September 2009, and so the days of the month are not required. If the three-month average spans the year-end, [e.g., December to February (DJF)] then the year will need to be included for the beginning and the end dates. For example, 2008-12/2009-02 is correct, but 2008-12/02 is invalid.
When CPT requests a start date the date is always for the beginning of the season. So, for example, to start in DJF 1971/72, the start date is December 1971.