The local time zone from the Control Panel on Windows systems.
.IP [6]
The C library's idea of the local time zone, as defined by the
\fBmktime\fR and \fBlocaltime\fR functions.
.PP
In case [1] \fIonly,\fR the string is tested to see if it is one 
of the strings:
.PP
.CS
 gmt     ut      utc     bst     wet     wat     at
 nft     nst     ndt     ast     adt     est     edt
 cst     cdt     mst     mdt     pst     pdt     yst
 ydt     hst     hdt     cat     ahst    nt      idlw
 cet     cest    met     mewt    mest    swt     sst
 eet     eest    bt      it      zp4     zp5     ist
 zp6     wast    wadt    jt      cct     jst     cast
 cadt    east    eadt    gst     nzt     nzst    nzdt
 idle
.CE
.PP
If it is a string in the above list, it designates a known
time zone, and is interpreted as such.
.PP
For time zones in case [1] that do not match any of the above strings, 
and always for cases [2]-[6], the following rules apply.
.PP
If the time zone begins with a colon, it is one of a