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Thanks peter, this is very similar. comments below. ----- Original Message ----- From: <address@hidden> To: "John Caron" <address@hidden> Sent: Saturday, June 08, 2002 8:43 AM Subject: Re: latest Catalog XML > Hi all, > > An interesting discussion. I wrestled a bit with this around the time > of the DODS developers meeting last January. I have attached a table > that I put together to help me keep track of the issues. I think that > you have progressed way beyond this, but thought that you might find > it interesting anyway. > > Peter > OPeNDAP Data Objects are the data retrieved by any OPeNDAP URL (constrained or unconstrained). == THREDDS dataset(meaning #3) > OPeNDAP Datasets (or OPeNDAP Granules) are OPeNDAP Data Objects accessed by an unconstrained URL. I envision that constrained URLs are also legitimate targets for THREDDS dataset elements. So a THREDDS dataset (meaning #2) has a constrained or unconstrained OPeNDAP URL. > OPeNDAP Data Collections are collections of OPeNDAP Datasets that are accessible either as a new OPeNDAP Dataset via an OPeNDAP Aggregation Server, or as a list of OPeNDAP Datasets via a File Server. An agg.server transparently makes dataset collections into THREDDS datasets. So THREDDS collections are just groups of related datasets. Im not sure how file servers work. > NVODS Datasets are all of the meteorological or oceanographic data at a site that the data provider considers to be logically connected. Could be an OPeNDAP Dataset, an OPeNDAP Data Collection or a group of OPeNDAP Datasets that are not formally linked from an OPeNDAP perspective. I think this would be a THREDDS Collection. thanks for your comments