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SU News 03/03/91

This note is more discursive than usual because I am looking
for advice (37 lines).

I am still uncertain about the recent change of using the float
fields f1,d1,f2,d2 to transfer information about non-seismic
data (usually because fft's have been done and their size is
not known to the user).  It almost immediately led to setting these
fields for seismic data too in order to get nice plot labels here.

Last time, I mentioned the potential confusion of setting the float f2,d2
fields in the unassigned portion of the header versus setting the offset
field in the standard portion of the header for programs such as sunmo
and sumute.  At CWP we usually like to label in km/sec, but since
the standard offset field must be an integer, we have to set offset
in meters.  Not so nice to have the equivalent information in two places
in two different measurement units.

I discovered a second problem recently while reading a file
from an outside SEG-Y tape.  I like to use:

$ segyread trmax=150 | sugain tpow=2 gpow=.5 | suximage

just to see if I am reading seismic data OK from a new tape.
Alas, on this tape, the outside users had something in the
unassigned field section and now that the plotting programs
use this area, I got a black plot with no labels.  I cured
my problem by setting f2,d2 with sushw, but this doesn't
constitute a general solution.  And segyread doesn't think about
what is IN the traces headers--it just copies them.  Maybe
a "segyclean" to zero out the unassigned portion?

suband tweaked (03/03/91)

New betas: Welcome to Cees de Bruin at Delft Univ and Gerd-Jan Lortzer at the
Applied Geoscience Institute also in Delft who both have recent copies of SU.