[[... [clock] ...]]

"The current set of places where it will try to find Olson files is:

    /usr/share/zoneinfo
    /user/share/lib/zoneinfo
    /user/lib/zoneinfo
    /user/local/etc/zoneinfo
    C:/Progra~1/cygwin/usr/local/etc/zoneinfo

That's what's done if a search for a [Tcl] time zone definition in '''$tcl_library/tzdata''' fails.

In addition, the set of hardcoded time zone names in '''::tcl::clock::LegacyTimeZone''' is recognized, as is any Posix
time zone specifier, and the special name 'localtime'."


"...'localtime' is not recommended ..."

"... if -timezone is not supplied, the order of preference is '''$env(TCL_TZ)*''';
'''$env(TZ)''';
the time zone from the [Windows] [registry]; ''':Tcl/Localtime''' (allowing a site to install
its own time zone definition in '''$tcl_library/tzdata'''),
and ''':localtime''' (the C library)"

"... this structure means that [Starpack]s for [Linux] and [Solaris]
[[and [Mac OS X] ]]
can safely omit '''$tcl_library/tzdata''' with minimal loss of functionality,
since those platforms have the Olson files always.
Windows and [HP-UX] need '''tzdata''' for full functionality, but can omit it 
if 8.4-level timezone functionality is adequate ..."