daylight - daylight savings time variable

Syntax	#include <time.h> extern int daylight;
Description	The external variable daylight indicates whether time should reflect daylight savings time. daylight is non-zero if an alternate time zone exists. The timezone names are contained in the external variable tzname, which is set by default as follows: char *tzname[2] = { "GMT", "    " }; daylight is set by tzset(),  ctime(), localtime(), mktime(), and strftime().
Notes	The system administrator must change the start and end date for daylight savings time each year if the Julian date format is used.
See also	altzone, asctime(), ctime(), gmtime(), localtime(), timezone, tzname, tzset(), time.h.