Plotted entries from OPSLOG files in VIMOS report MASK_ZERO, plot 8, data set parY0Q4:

DATE       MJD-OBS      parameter values
==========================================================================
2008-11-20 54790.928079 1377.26509872226	parY0Q4
2008-11-21 54791.890067 1377.10097527509	parY0Q4