Using ParameterGroup to annotate ancillary data (such as quality flags) of a variable

We've been considering the use of ParameterGroup to annotate quality flag variables which are directly associated to, for example, observational variables. In the CF conventions this is referred to as ancillary data.

The spec also uses an example with mean values and an associated stddev. So this seems to indicate that the intended use of ParameterGroups can be the same as the ancillary data that the CF conventions describe.

What's missing from the current specification is to indicate which variable of a ParameterGroup is the primary variable and which are the supporting ('ancillary') variables. What are your thoughts on this? Would it help to define this somehow in a ParameterGroup? For example by defining that the first member of a group is the primary variable. Another option would be to do this similarly as the CF conventions and add an attribute ancillaryVariables: list[str] to Parameter.

I've commented on an existing and related issue https://github.com/opengeospatial/ogcapi-environmental-data-retrieval/issues/634#issuecomment-3442567024 in the EDR spec which talks about how ParameterGroup can be used in EDR.

Inizia esaminando la definizione attuale di ParameterGroup, quindi confronta la sezione ancillary data delle CF conventions con l’esempio collegato della specifica OGC API EDR. Leggi la discussione della issue EDR correlata per avere il contesto. Il lavoro sarà considerato concluso quando si sarà raggiunto un accordo su come identificare una variabile primaria e le variabili di supporto, e tale decisione sarà stata registrata nella specifica CoverageJSON.