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Annotation of 43BSDTahoe/man/man5/tzfile.5, revision 1.1.1.1

1.1       root        1: .\"    @(#)tzfile.5    1.2 (Berkeley) 3/11/87
                      2: .\"
                      3: .TH TZFILE 5
                      4: .AT 5
                      5: .SH NAME
                      6: tzfile \- time zone information
                      7: .SH SYNOPSIS
                      8: .B
                      9: #include <tzfile.h>
                     10: .SH DESCRIPTION
                     11: The time zone information files used by
                     12: .IR tzset (3)
                     13: begin with bytes reserved for future use,
                     14: followed by three four-byte values of type
                     15: .BR long ,
                     16: written in a ``standard'' byte order
                     17: (the high-order byte of the value is written first).
                     18: These values are,
                     19: in order:
                     20: .TP
                     21: .I tzh_timecnt
                     22: The number of "transition times" for which data is stored
                     23: in the file.
                     24: .TP
                     25: .I tzh_typecnt
                     26: The number of "local time types" for which data is stored
                     27: in the file (must not be zero).
                     28: .TP
                     29: .I tzh_charcnt
                     30: The number of characters of "time zone abbreviation strings"
                     31: stored in the file.
                     32: .PP
                     33: The above header is followed by
                     34: .I tzh_timecnt
                     35: four-byte values of type
                     36: .BR long ,
                     37: sorted in ascending order.
                     38: These values are written in ``standard'' byte order.
                     39: Each is used as a transition time (as returned by
                     40: .IR time (2))
                     41: at which the rules for computing local time change.
                     42: Next come
                     43: .I tzh_timecnt
                     44: one-byte values of type
                     45: .BR "unsigned char" ;
                     46: each one tells which of the different types of ``local time'' types
                     47: described in the file is associated with the same-indexed transition time.
                     48: These values serve as indices into an array of
                     49: .I ttinfo
                     50: structures that appears next in the file; 
                     51: these structures are defined as follows:
                     52: .in +.5i
                     53: .sp
                     54: .nf
                     55: .ta .5i +\w'unsigned int\0\0'u
                     56: struct ttinfo {        
                     57:        long    tt_gmtoff;
                     58:        int     tt_isdst;
                     59:        unsigned int    tt_abbrind;
                     60: };
                     61: .in -.5i
                     62: .fi
                     63: .sp
                     64: Each structure is written as a four-byte value for
                     65: .I tt_gmtoff
                     66: of type
                     67: .BR long ,
                     68: in a standard byte order, followed by a one-byte value for
                     69: .I tt_isdst
                     70: and a one-byte value for
                     71: .IR tt_abbrind .
                     72: In each structure,
                     73: .I tt_gmtoff
                     74: gives the number of seconds to be added to GMT,
                     75: .I tt_isdst
                     76: tells whether
                     77: .I tm_isdst
                     78: should be set by
                     79: .I localtime (3)
                     80: and
                     81: .I tt_abbrind
                     82: serves as an index into the array of time zone abbreviation characters
                     83: that follow the
                     84: .I ttinfo
                     85: structure(s) in the file.
                     86: .PP
                     87: .I Localtime
                     88: uses the first standard-time
                     89: .I ttinfo
                     90: structure in the file
                     91: (or simply the first
                     92: .I ttinfo
                     93: structure in the absence of a standard-time structure)
                     94: if either
                     95: .I tzh_timecnt
                     96: is zero or the time argument is less than the first transition time recorded
                     97: in the file.
                     98: .SH SEE ALSO
                     99: ctime(3)

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