Dear Bill Yes, I agree with you, the values of a CF coordinate variable (not an auxiliary coordinate variable) must all be different, as the NUG says; CF generally upholds the NUG. In principle this is because the coordinate variables are the independent variables on which the data values depend. Independent variables should be single-valued.
You could propose a CF trac defect ticket to modify the text of the CF standard in order to clarify this. Best wishes Jonathan > In CF Metadata Conventions section 1.2. Terminology, a coordinate > variable "is defined as a numeric data type with values that are ordered > monotonically." > > This suggests that weak-monotonicity is acceptable. > > Within the same section and paragraph, reference is made to section > 2.3.1. of the NUG, which states that coordinate variables "are numeric > vectors and strictly monotonic (all values are different and either > increasing or decreasing)." > > This states that strict-monotonicity is required. > > The definition of a CF coordinate variable is fundamental to the CF > model, and yet its specification from the wording in the conventions > document is unclear. > > I feel that explicit clarification on this matter within the CF Metadata > Conventions document is well overdue. _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
