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#95: Development of CF 1.5 Data Model -----------------------------+---------------------------------------------- Reporter: markh | Owner: [email protected] Type: task | Status: new Priority: medium | Milestone: Component: cf-conventions | Version: Resolution: | Keywords: -----------------------------+---------------------------------------------- Comment (by graybeal): {{{When an attribute appears both globally and as a variable attribute, the variable's version has precedence}}} >>It's a worrying consequence of the all-attributes-are-really-data- attributes approach that it renders the global attribute meaningless. >I think that's stretching the point a bit far. It's certainly true that one needs to think a bit harder about what it means to "take precedence". This example clearly indicates that it should not mean destroy. Though ambiguous, I've always thought it meant the global attribute is lost. Which I thought was bad design, because I'm convinced global attributes should be managed as Jon Blower describes. If global and variable attributes exist and differ, maybe "whoever wrote the data messed up", or maybe they followed the description to provide a default value and override values. I see "how do we handle global attributes during processing?" as a red herring. If collections get remerged into new combinations, then global attributes can be handled via provenance, describing where the newly merged variable attributes came from (and if desired, the attributes of those sources). Whereas, if the task is to merge a group of uniform collections into a single collection, the global attributes should already be identical or vary in known and manageable ways; if not, one is back to the provenance solution. So if the CF data model is only describing past practices, you can forget about that -- the original was too ambiguous to present a single correct answer. (In which case provide the new answer, and people can satisfy the ambiguity however they feel is right.) If the data model provides the best way forward, it should definitely support Jon's list. -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/95#comment:87> 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.
