I thought I understood the comment in the file structure, ** one (char [4]) total correction after above ** tzh_ttisstdcnt (char)s indexed by type; if TRUE, transition ** time is standard time, if FALSE, ** transition time is wall clock time ** if absent, transition times are ** assumed to be wall clock time ** tzh_ttisgmtcnt (char)s indexed by type; if TRUE, transition ** time is UTC, if FALSE, ** transition time is local time ** if absent, transition times are ** assumed to be local time but, I don't see them being used the logic to search ats, or to adjust the ats values after loading. So if present in the data file they do nothing. In fact, I got rid of the TRUE's in one of the data files, and it did not make the program produce any different results. What am I missing? Thanks, --John