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#104: Clarify the interpretation of scalar coordinate variables -----------------------------+---------------------------------------------- Reporter: jonathan | Owner: [email protected] Type: defect | Status: new Priority: medium | Milestone: Component: cf-conventions | Version: Resolution: | Keywords: -----------------------------+---------------------------------------------- Comment (by jonathan): Dear Jim et al. Replying to [comment:17 biard]: > The point under dispute is whether scalar coordinate variables should be assumed to have (implied) size-one dimensions that are independent of one another, or whether there should be no assumption at all made about dependence or independence of the implied dimensions. > > Does that sum it up, or is there something more? Yes, I think that's right. That's the contentious point. It has an implication for the CF logical data model (that is, an abstraction of the way we encode the metadata in a netCDF file). Mark and Ed think that scalar coordinate variables are a distinct concept in the logical data model from coordinate variables and auxiliary coordinate variables. David and I think that scalar coordinate variables are a convenient shorthand for coordinate variables and auxiliary coordinate variables, and not a distinct concept of the logical data model. Like Mark, Steve thinks that defining this either way is a material change rather than a clarification or a correction of the convention. Steve writes > This is a genuine flaw in the current CF specification. It deserves to be fixed. The text at the start of this trac ticket is wrong when it says that it is not proposing a material change. But it is a needed change. I think it isn't a change in the convention, myself, but since it is contentious I'm happy to change this ticket to a proposal for amendment rather than a defect ticket. That means it needs to be positively agreed, rather than agreed by default if not objected to. At the moment, it can't be agreed as a defect ticket anyway because there are outstanding objections. As Steve says, > [This ticket] addresses an ambiguity created by the definitions of auxiliary coordinate variable and scalar coordinate variable. Our intention is to remove that ambiguity by clarifying that scalar coordinate variables represent size-one numeric coordinate variables and size-one string-valued auxiliary coordinate variables. We don't think that in practice this will limit the flexibility that software has in interpreting CF-netCDF files, and it doesn't make any existing file invalid. Really it's only an issue for the logical data model, we think. Best wishes Jonathan -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/104#comment:18> CF Metadata <http://cf-pcmdi.llnl.gov/> CF Metadata This message came from the CF Trac system. To unsubscribe, without unsubscribing to the regular cf-metadata list, send a message to "[email protected]" with "unsubscribe cf-metadata" in the body of your message.
