The IANA time zone database maps a name to the named location's historical and predicted clock shifts. This database is used by many computer software systems, including most Unix-like operating systems, Java, and the Oracle RDBMS; HP's "tztab" database is similar but incompatible. When temporal authorities change DST rules, zoneinfo updates are installed as part of ordinary system maintenance. In Unix-like systems the TZ environment variable specifies the location name, as in TZ=':America/New_York'. In many of those systems there is also a system-wide setting that is applied if the TZ environment variable isn't set: this setting is controlled by the contents of the /etc/localtime file, which is usually a symbolic link or hard link to one of the zoneinfo files. Internal time is stored in timezone-independent epoch time; the TZ is used by each of potentially many simultaneous users and processes to independently localize time display. COUNT 5
QSN1 The IANA database works by connecting names to what information about the location? ANS1 historical and predicted clock shifts QSN2 IANA, or zoneinfo, updates are installed as a part of what ordinary function when changes to DST policy are made? ANS2 system maintenance QSN3 What environment variable defines a location's name? ANS3 TZ QSN4 What format is used to store internal time in systems that use zoneinfo? ANS4 timezone-independent epoch time QSN5 What's the name of the HP database that's similar to IANA but not compatible with it? ANS5 tztab