http://kor.i2p/books/The%20C%20Programming%20Language%20by%20K&R/appb.html
Some functions process local time , which may differ from
calendar time, for example because of time zone. clock_t and time_t are arithmetic types representing times, and struct tm holds the components of a calendar time: int tm_sec; seconds after the minute (0,61) int tm_min; minutes after the hour (0,59) int tm_hour; hours since midnight (0,23) int tm_mday; day of the month (1,31) int tm_mon; months since January (0,11) int tm_year; years since 1900 int tm_wday; days since Sunday (0,6)...