Values are generated for both CHIP1 and CHIP2, 2x2 binning only. <a
href="http://www.eso.org/observing/dfo/quality/FORS2/qc/zeropoints/zeropoints.html">Photometric
nights</a> are selected from the Absorption Monitor.  Zeropoints are
for flux in e-/sec, not in ADU.  Do <b> not use these zeropoints for
science data</b>. They are reduced assuming a standard extinction
value, which may not be correct for an individual night!

More information can be found on
the <a href="http://www.eso.org/observing/dfo/quality/FORS2/qc/zeropoints/zeropoints.html">plot tutorial page</a>