Robin Shirley ([EMAIL PROTECTED]) writes:
> However, I have to say that I'd feel happier about supporting CIF as a common
> file format if (a) it were considerably simpler to read and (b) the CIF
> committee were more responsive to practical powder-related issues.
I do owe Robin an apology for my inaction. I have still not completed
all the tasks I have promised with respect to pdCIF v1.0 and so I have
not started work on v1.1, which will incorporate some of the additions
suggested by Robin and others. CIF is something that I work on at home,
not as part of my employment and time for it is scarce. A volunteer to
take over for me would be very welcome.
L. Cranswick wrote:
> PS: With respect to Robin's comments on trying to get additions
> to PowderCIF for Powder Indexing,;what is the present mechanism
> for getting things implemented into the Powder CIF area?
As of right now, the procedure is to read through the pdCIF dictionary
to determine what it is you want to store that is not present and then
define the term to be added. You then write to me with a case for why
the terms are necessary and then let your e-mail age in CIF inbox for a
while. A IUCr committee (pdDMG) will eventually evalute these
suggestions. I hope to be ready to start this soon.
I would like to note that while there is a lot of information that can
be stored in a powder CIF, software that reads CIFs needs only to deal
with the relevant fields for the task at hand and can ignore the rest.
While CIF has provisions for including structural information, peak and
reflection tables,... life does not need to be so complex. For storage
of raw lab data, one can write a very simple CIF file that looks like
this:
data_myCIF
_pd_meas_2theta_range_min 5.0
_pd_meas_2theta_range_max 65.0
_pd_meas_2theta_range_step 0.02
loop_ _pd_meas_counts_total
10 16 23 18 ...
That's it! Not so complex.
Of course it would be a good idea to use the appropriate CIF terms to
describe if the data are x-ray or neutron, specify wavelengths used, if
a theta-compensating slit was used,... As many people keep
rediscovering, ambiguous data can be very hard to use.
> (Does NEXUS just handle data - or can it include structure
> information?)
There is no reason that NeXus could not include any kind of information,
but no provisions exist as far as I know. It is really being implemented
as a raw data format.
Brian
********************************************************************
Brian H. Toby, Ph.D. Leader, Crystallography Team
[EMAIL PROTECTED] NIST Center for Neutron Research, Stop 8562
voice: 301-975-4297 National Institute of Standards & Technology
FAX: 301-921-9847 Gaithersburg, MD 20899-8562
********************************************************************
