Alternate Entry Name: _TZISDST
B: %b/manif/t_ctrl type = .tzisdst(tzref);
C: #include <t_ctrl.h> int _tzisdst(_T_time_zone tzref);
tzref = .tzqry("EST"); type = .tzisdst(tzref);
.TZISDST determines if a particular time zone is standard time or daylight savings time. Time zones marked with the DST flag in the time zone definition file are considered daylight savings zones; others are standard zones.
A negative value can be returned in several cases. If the program is operating in the "error" locale or the "tzref" value was produced by passing an unknown name to .TZQRY, then .TZISDST will return a negative value. The program may be operating in the "error" locale if the time zone data file is not available, or access was suppressed by use of the .NO_TZ external.
Copyright © 1996, Thinkage Ltd.