ISO 8601 is the international standardisation for dates and time released by the International Standards Organisation in 1988.
Dates are given in the format YYYY-MM-DD, as such the 13th of November 2007 would be written as 2007-11-13, or in a truncated form such as 20071113. If a parametre is a single digit a padding zero is used, for example 2 is written as 02.
Time is written in the format HH:MM:SS using 24 hours time, as such 16 minutes and 37 seconds past one in the afternoon would be written as 13:16:37, or in truncated form as 131637. Again padding zeros are used if the parametre is a single digit. It is permissible to write fractions of a time period using a comma, eg 13:14:15,16 indicates 13 minutes and 15 and 16/100 seconds past one in the afternoon, similarly 10,5 indicates 5/10 of an hours past 10 in the morning, or 10:30. The symbol "Z" indicates the use of universal coordinated time.
Time and dates can be written as a single expression by using the symbol "T" to separate the two strings. For example, 56 minutes and 4 seconds past 2 in the afternoon is written as 145604, whereas the 13th of November 2007 is written as 20071113, combined these read as 20071113T145604.
A time period can be indicated using a forward slash "/" between two instances, for instance 20071113T145604/20071113T165604 indicates a time period of two hours spanning between those two times.