Richard, Jonathan, et. al.,
As the famed Henning piece on CORBA stated -- in standards committees
"no" is a preferable answer to "yes" all other things considered. More
generality can often lead to less interoperability in CF or other data
standards.
Having CF time axes that run backwards will break a lot of software. It
will be a net disruption to interoperability. So the question: "is
there a sufficiently compelling use case for admitting it?", where we
interpret "compelling" in the context of balancing the general loss of
interoperability against the gains to particular datasets from adding
this bit of flexibility.
- Steve
========================================================
On 5/1/2012 8:02 AM, Jonathan Gregory wrote:
Dear Richard
The CF definitions of discrete sampling geometries define the "trajectory" feature type as "a series of
data points along a path through space with monotonically increasing times". This is a stricter stance than the
usual CF coordinate definition of "ordered monotonically". What was the reason behind the addition of the
"increasing" constraint, and can it be relaxed? We have data sets where a model is run backwards in time.
Good point. I would think that "monotonically" would be enough, not necessarily
increasing. I can't remember a reason for "increasing"; I assume it's just
because sect 9 was conceived for observations in the first place. However, John
Caron may well have a comment. I don't think anything prevents your storing
the data in the orthogonal multidimensional representation, which existed
before sect 9 did and doesn't require increasing coordinates.
Best wishes
Jonathan
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