Older or stripped-down systems may support only the TZ values required by POSIX, which specify at most one start and end rule explicitly in the value. For example, TZ='EST5EDT,M3.2.0/02:00,M11.1.0/02:00' specifies time for the eastern United States starting in 2007. Such a TZ value must be changed whenever DST rules change, and the new value applies to all years, mishandling some older timestamps.
కొత్త డిఎస్టి నిబంధనలతో మారినప్పుడు కొత్త TZ విలువ తప్పుగా నిర్వహించబడుతుందా?
older timestamps