Times and dates are handled by PSPP as single numbers. A time is an interval. PSPP measures times in seconds. Thus, the following intervals correspond with the numeric values given:
10 minutes 600
1 hour 3,600
1 day, 3 hours, 10 seconds 97,210
40 days 3,456,000
A date, on the other hand, is a particular instant in the past or the future. PSPP represents a date as a number of seconds since midnight preceding 14 Oct 1582. Because midnight preceding the dates given below correspond with the numeric PSPP dates given:
15 Oct 1582 86,400
4 Jul 1776 6,113,318,400
1 Jan 1900 10,010,390,400
1 Oct 1978 12,495,427,200
24 Aug 1995 13,028,601,600