The issue of what time zone to use if the TZ variable is not set should be thought out a bit more. ATT has decided to use a "default" of GMT if no TZ is set or if it is NULL ( "TZ=" ). Our reasoning is that in the majority of cases this is an error by the system administrator in setting or exporting the TZ variable and it is necessary for someone to notice the error. As it stands most developers/porters set the TZ to their local time zone (who is it that uses PST?!) and then never notice that their product has problems. Using wall clock as default merely propogates this development problem and results in products having problems when they are used in other environments. The use of wall clock as the "default" ought to be a concious choice by a programmer and GMT ought to be the default whenever a time routine can't decide what timezone to use.