There are three common formats across SAS, SPSS and Stata.
Date (number of days)
Time (number of seconds):
DateTime (number of seconds):
Dates and date times use a difference offset to R:
SAS: https://support.sas.com/documentation/cdl/en/lrcon/65287/HTML/default/viewer.htm#p1wj0wt2ebe2a0n1lv4lem9hdc0v.htm
SPSS: https://www.ibm.com/docs/en/spss-statistics/29.0.0?topic=wizard-dates-times-in-spss-statistics https://www.ibm.com/docs/en/spss-statistics/29.0.0?topic=formats-date-time
Stata: https://www.stata.com/manuals/u25.pdf