Added a quadraticSpline enumerated value to the
interpolate attributes of the <independentVarPts> and
<independentVarRef>
elements in response to a request from Geoff Brian of DSTO; fixed typo in
cubicSpline attribute string. Added reference to Wikipedia article on spline interpolation.
Added a classification attribute to the <reference> element; added a
date attribute to the <modificationRecord>
element, per suggestions by Geoff Brian of DSTO.
Added two-D and three-D ungridded table examples and figures; corrected typo on ungridded table definition syntax (thanks to Dr. Peter Grant of U. Toronto's UTIAS and Geoff Brian of Australia's DSTO).
Reintroduced <!ENTITY> to include MathML2 DTD (complete) in body of this DTD. This entity definition quietly went away in version 1.6 due to a misunderstanding of proper way to include external DTDs; it is reintroduced to assist validating parsers.
Added <description>
sub-element to the <provenance> element, so the
provenance entry can contain more information about change justification documents;
made <provenance> or <provenanceRef> acceptable
sub-elements to <variableDef> and <checkData> elements after a
request from Geoff Brian of DSTO.