Hello again. I just looked at 'Kernel::System::AuthSession::FS' => 'sub CheckSessionID' => 'check session idle time'. It uses the same calculation as used in 'Kernel::System::AuthSession::IPC'. When tracing the code, the 'UserSessionStart' in 'sub CheckSessionID' is defined in both 'customer.pl' and 'index.pl' which references 'SystemTime()' which incorporates the 'Timezone' parameter in 'Kernel::System::Time.' CONCLUSION: Either a workaround or an alternative is needed for displaying US timezones when OTRS is running on a webserver whose localtime is set to GMT+0. This variation in timezones would also affect ticket submission; the respondent's times via web interface; log timestamps; etc. in those cases where the OTRS administrator would prefer to have all of the timestamps to be recorded in the timezone of choice. Thanks.