[1] M Technology and MUMPS Language FAQ, Part 1/2 () <https://web.archive.org/web/20150828234407/http://www.vmth.ucdavis.edu:80/m/m_faq1.htm>

In M, the current date and time is contained in a special system variable,

$H (for "HOROLOG"). The format is a pair of integers separated by a comma,

e.g. "54321,12345" The first number is the number of days since December

31st, 1840, i.e. day number 1 is January 1st, 1841; the second is the number

of seconds since midnight.