Guardian Procedure Calls Reference Manual

Example
#include <cextdecs (DST_TRANSITION_MODIFY_)>
zsys_ddl_dst_entry_def olddstentry, newdstentry;
short error;
long long oldTimeStampLow, oldTimeStampHigh;
long long newTimeStampLow, newTimeStampHigh;
olddstentry.z_lowgmt = oldTimeStampLow;
olddstentry.z_highgmt = oldTimeStampHigh;
olddstentry.z_offset = 3600; /* seconds */
olddstentry.z_version = ZSYS_VAL_DST_VERSION_SEP1997;
newdstentry.z_lowgmt = newTimeStampLow;
newdstentry.z_highgmt = newTimeStampHigh;
newdstentry.z_offset = 3600; /* seconds */
newdstentry.z_version = ZSYS_VAL_DST_VERSION_SEP1997;
error = DST_TRANSITION_MODIFY_ ((short*)&olddstentry,
DST_TRANSITION_MODIFY_ Procedure 335