Assertion: hour | /r/CapableOf | incorporate positive or negative leap
Facets:
value: on rare occasions
type: TEMPORAL
Source sentences:
text: However, on rare occasions an hour may incorporate a positive or negative leap second,[a] making it last 3,599 or 3,601 seconds, in order to keep it within 0.9 seconds of UT1, which is based on measurements of the mean solar day.