Overview#Minute is defined in RFC 3339 as A period of time of 60 seconds. However, see also the restrictions in section 5.7 and Appendix D for how leap seconds are denoted within minutes.
Minute is equal to 1⁄60 (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a negative leap second, which would result in a 59-second minute, but this has never happened in more than 40 years under this system). 
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