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#74: Allow sharing of ancillary variables among multiple data variables ---------------------------------------+------------------------------------ Reporter: [email protected] | Owner: [email protected] Type: enhancement | Status: new Priority: medium | Milestone: Component: cf-conventions | Version: Resolution: | Keywords: "ancillary data" "standard name modifiers" ---------------------------------------+------------------------------------ Comment (by biard): Jonathan, Your last comment has helped me understand (and agree with) Nan's objection. As near as I can tell, a standard name is a sort of type or class. It describes the contents of a variable by telling you what class of measurement it belongs to, but I think its reliable use must end there. If two variables share a standard name (or share a root standard name), it tells you about comparability, but it doesn't reliably tell you anything about linkage. The only situation in which it might be safe to infer linkage from standard names is when there is only one primary variable in a file with a given standard name, and in which all of the ancillary variables for that primary variable have standard names that are modifications of the primary. There are a number of conditions that invalidate this approach. For example: 1) More than one primary variable with the same standard name. (Which each need their own ancillary variables.) 2) A primary variable that has a standard name that is a modification of the standard name associated with another primary variable. 3) An ancillary variable has the same standard name as its primary. 3) An ancillary variable has a standard name that is completely different from its primary. It seems pretty clear to me that the ancillary_variables attribute is not a convenience feature. It is the only general way available in CF to unambiguously declare the linkages. Given all that, I don't have any problem with promoting status_flag and number_of_observations to the level of standard names. Grace and peace, Jim -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/74#comment:27> 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.
