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Hi all, I've put my presentation about implementing coordinate systems in HDF5 up on our FTP server at: ftp://hdf.ncsa.uiuc.edu/pub/outgoing/koziol/CoordSys.ppt One important thing to note about this presentation: it's got the actual coordinate system extension embedded in the midst of some "infrastructure" extensions for HDF5 (like the "Formula" data storage and shared dataspaces and dimensions) that would be nice for various aspects of dealing with coordinate systems in HDF5 files. The infrastructure extensions are nice, but not critical to the implementation of the coordinate system work in HDF5 (and are especially not important to thinking about the data model of the new coordinate system stuff). The core "objects" [classes, really] to think about for the coordinate system extension are: Coordinate System, Axis, and Scale. Also, the slides about "Sharability in HDF5" in this presentation are mostly intended for internal HDF5 library use and should be able to be skipped over without much concern, until our telecon next week. Quincey P.S. - Here's the list of issues which have been brought up, but I didn't change in the presentation yet: - Find a good description/picture to show "real space" & how it gets mapped to dataspace - Find a better way to describe the netCDF coord. system model (to better reflect how all the coordinate variables really compose a single coordinate system and each "normal" variable uses them to take a "slice" through the total space defined by the coordinate variables). - Possibly find a way to map sub-dataspaces onto another dataspace, including re-mapping indices and sub-setting, etc. (to come more closely to the netCDF model of defining all the dimensions and choosing subset of them for each dataset) - Fix labels on Sierra use case to be different. - Allow dataspace rank to be greater than coordinate system rank and add use case (mapping a n-D coordinate to an offset on a space- filling curve, for example). - Change "Index Map" term to be "Index Array" - Possibly define a mechanism to "locate" one coordinate system within another coordinate system, in order to show that the elements for several dataspaces were located within a single, shared coordinate system.