1 xz is a command line tool with syntax similar to that of gzip. 2  xzdec is a decompression-only tool smaller than the full-featured xz tool. 3  A set of shell scripts (xzgrep, xzdiff, etc.) have been adapted from gzip to ease viewing, grepping, and comparing compressed files.
Epoch (astronomy), a moment in time used as a reference for the orbital elements of a celestial body. Epoch (cosmology) or cosmologic epoch, a phase in the development of the universe since the Big Bang. Epoch (geology) or geologic epoch, a span of time smaller than a period and larger than an age.
Epochs are subdivisions of geologic periods. Era-A division of geologic time of several hundred million years in duration. An era is smaller than an eon and longer than a period. Geologic Time Scale-A categorization of geological events based on successively smaller time spans: eons, eras, periods, epochs, and ages.Hadean-The earliest eon in the history of the Earth from the first accretion of planetary material until the date of the oldest known rocks.eologic Time Scale-A categorization of geological events based on successively smaller time spans: eons, eras, periods, epochs, and ages. Hadean-The earliest eon in the history of the Earth from the first accretion of planetary material until the date of the oldest known rocks.