Hi Folks
I think everything Russ has suggested here makes excellent sense! The last
suggestion deals with all issues I've got about links from
ancillary_variables back to "primary" variables ...
Bryan
On Tuesday 08 April 2003 3:55 pm, Russ Rew wrote:
> Hi,
>
> I haven't followed this discussion very closely, but have a few
> comments on one of Jonathan's suggestions.
>
> > If we include data quality variables, we are dealing with more than just
> > "errors". I would suggest calling the pointer attribute "ancillary_data"
> > rather than "error_variables".
>
> If an attribute contains a list of netCDF variables, I suggest it's
> better to use "variables" in the attribute name, because otherwise
> it's just a string with no indication it is intended to refer to other
> variables. So I would much prefer "ancillary_variables" to
> "ancillary_data". Similarly, if an attribute contains a list of other
> attribute or dimension names, using a suffix of "_attributes" or
> "_dimensions" in the attribute name makes the intention clear. If an
> attribute can only name one variable, dimension, or attribute, then
> you could use "_variable", "_dimension", "_attribute" to indicate
> the intention that only one component is named, as in one-to-one or
> many-to-one mappings.
>
> I suspect this meta-convention hasn't been followed in all the
> coordinate variables conventions that have been proposed (although
> "_coordinates" is a good prefix, since it can name variables or
> dimensions), but if followed, it would permit extra checking analogous
> to what declarations in programming languages provide, that a variable
> name in such a list exists. And it would make clear that such an
> attribute exists for structural purposes, to establish additional
> relations among the components in a dataset. It could even be used to
> prevent components becoming separated from closely associated
> components when processing splits a file, since it would permit
> automatic determination of closely associated variables.
>
> > * Give the ancillary variables a standard_name prefix of
> > "ancillary_data_for_". They should also have all the metadata of their
> > parent variables, so they are independently fully self-described.
>
> Instead of prefixing a variable name with "ancillary_data_for", I
> would instead recommend using an attribute named something like
> "for_variable" or "for_variables" that names the variable or variables
> to which the information applies.
>
> --Russ
>
> _____________________________________________________________________
>
> Russ Rew UCAR Unidata Program
> russ at unidata.ucar.edu http://my.unidata.ucar.edu
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--
Bryan Lawrence, Head NCAS/British Atmospheric Data Centre
web: www.badc.nerc.ac.uk phone: +44 1235 445012
CLRC: Rutherford Appleton Laboratory, Chilton, Didcot, OX110QX, UK
Received on Wed Apr 09 2003 - 00:25:18 BST
