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<TITLE>RE: [NeXus-committee] Status of base definitions</TITLE>
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<P><FONT SIZE=2>Peter,</FONT>
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<P><FONT SIZE=2>What is the method proposed for ratifying the issues in the second and third paragraphs? Seems reasonable to put these up as swiki pages for comment and vote.</FONT></P>
<P><FONT SIZE=2>Regards,</FONT>
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<P><FONT SIZE=2>Nick Hauser.</FONT>
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<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Peterson, Peter F. [<A HREF="mailto:petersonpf@ornl.gov">mailto:petersonpf@ornl.gov</A>] </FONT>
<BR><FONT SIZE=2>Sent: Tuesday, 13 July 2004 8:26 AM</FONT>
<BR><FONT SIZE=2>To: nexus-committee@anl.gov</FONT>
<BR><FONT SIZE=2>Subject: [NeXus-committee] Status of base definitions</FONT>
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<P><FONT SIZE=2>Please read the entire next paragraph.</FONT>
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<P><FONT SIZE=2>We have ratified all of the base classes and I just finished changing the definitions so they are valid XML files and make them consistent with the decision that base definitions will not specify bit lengths (NX_FLOAT, not NX_FLOAT32). As promised we are currently in a period of review before a final vote to ratify all of the base classes once and for all. During the review period *all* of the ratified base classes are locked, with the add comment field reinabled. There is also an "proposed ammendment" page <<A HREF="http://www.neutron.anl.gov.:8080/NeXus/82" TARGET="_blank">http://www.neutron.anl.gov.:8080/NeXus/82</A>> for suggesting ammendments to the base classes. The review period will end on August 2, 2004 at 9:00AM central. At that point there will be a vote on the ammendments, implementation of the ammendments, then a final display of what the changed base classes are.</FONT></P>
<P><FONT SIZE=2>Now for those that read entire messages...Before releasing this work to the public we still need to settle the following:</FONT></P>
<P><FONT SIZE=2> - units: At the NIAC meeting in CalTech we determined that units will be specified in the singular form, without abbreviation. However, in the current classes they are listed with wide variety; e.g. "cm", "Angstrom3", and "10^n*meter". This needs to be settled and the decision propagated through all of the classes.</FONT></P>
<P><FONT SIZE=2> - group and field names are to be specified without abbreviation and using underscores to separate words. Currently there are things like "x_cen" which violate this convention.</FONT></P>
<P><FONT SIZE=2> - When restricting the allowed values for fields there is two conventions for string values: "calibration sample" and "calibration_sample". One needs to be chosen.</FONT></P>
<P><FONT SIZE=2> - There is no method for specifying chemical composition of a sample. </FONT>
<BR><FONT SIZE=2> - Connecting data to detector was only specified for point detectors. This needs to be generalized to multiple area detectors.</FONT></P>
<P><FONT SIZE=2> - For single crystal experiments there must be a way to specify the goiniometer settings, frequently known as the sample orientation. There is no place to put this at the moment.</FONT></P>
<P><FONT SIZE=2>Also, to abuse my position, people have suggested the following:</FONT>
<BR><FONT SIZE=2> - NeXus files can be used for storing reduced and processed data. To do this properly there needs to be a mechanism for storing an "audit trail" of where the file came from, what programs were used (including versions), and any other external parameters used in the process.</FONT></P>
<P><FONT SIZE=2> - Related to the previous item, a audit trail of how and when the calibration for the instrument found in the file was done.</FONT></P>
<P><FONT SIZE=2> - To ease the job of finding instrument characterization measurements (background and incident spectrum), information to locate those measurements can be stored in the file.</FONT></P>
<P><FONT SIZE=2> - For large files there is a desire to have a "thumbnail" view of the data without loading the entire NXdata and resampling. Various requests have come in for a place to put a thumbnail image for each NXentry. An example is a 640x480 jpeg: <thumbnail type="NX_BINARY" mime_type="image/jpeg"/>.</FONT></P>
<P><FONT SIZE=2>Peter Peterson</FONT>
<BR><FONT SIZE=2>Executive Secretary, NIAC</FONT>
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<P><FONT SIZE=2>_______________________________________________</FONT>
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