When is PROBLEM Valid?
There can be some uncertainty about the validity of the manually
set PROBLEM keyword bits when level 1 processing has been
redone. Is the evaluation of a particular characteristic of
the data still valid? Maybe the data are better or worse now.
Simply throwing out the existing PROBLEM (and/or PROV_VLD) bits is
certainly unacceptable; however, some indication that the data
may need to be re-evaluated is required.
Bit 31 in PROBLEM (and thus in QUALITY) is used to indicate
whether the manually set bits ought to be reconsidered.
WHENEVER the DATA_SW keyword is set (e.g. due to reprocessing of the
level 1 data), bit 31 in PROB_VLD will be set to 0 by gather_qual.
Whenever PROBLEM is set by prob_upd,
bit 31 in PROBLEM and PROB_VLD will be set to 1.
prob_upd needs a means by which a range of data records can efficiently
have bits set in PROBLEM and PROB_VLD.
- This will make
it easier to indicate that a range of data have been evaluated and no
PROBLEM bits require setting. In this case only PROB_VLD needs to be specified and
T_PROB will be set.
- When only recertifying the continued validity of PROBLEM bits when
a processing change has called the value of PROBLEM into question
the T_PROB should not be changed.
This can be accomplished when prob_upd is called with no
PROBLEM or PROB_VLD parameters.
Since bit 31 will be set automatically and never specified on a command
line, it shouldn't be a problem to set the highest bit in this way.
Back to QUALITY.
Author JTH; Last modified by KRL on 4 Jun, 1998