Homepage: https://www.gnu.org/software/emacs
Author: Lars Magne Ingebrigtsen, Masanobu Umeda
Date and time handling functions
Time values come in several formats. The oldest format is a cons cell of the form (HIGH . LOW). This format is obsolete, but still supported. The other formats are the lists (HIGH LOW), (HIGH LOW USEC), and (HIGH LOW USEC PSEC). These formats specify the time value equal to HIGH * 2^16 + LOW + USEC * 10^-6 + PSEC * 10^-12 seconds, where missing components are treated as zero. HIGH can be negative, either because the value is a time difference, or because it represents a time stamp before the epoch. Typically, there are more time values than the underlying system time type supports, but the reverse can also be true.