This file contains a high-level description of this package's evolution. Releases are in reverse chronological order (most recent first). Note that, as of netcdf 4.2, the `netcdf-c++` and `netcdf-fortran` libraries have been separated into their own libraries.
* [Bug Fix] Fix multiple bugs in libnczarr. See [Github #2066](https://github.com/Unidata/netcdf-c/pull/2066).
* [Enhancement] Support windows network paths (e.g. \\svc\...). See [Github #2065](https://github.com/Unidata/netcdf-c/pull/2065).
* [Enhancement] Convert to a new representation of the NCZarr meta-data extensions: version 2. Read-only backward compatibility is provided. See [Github #2032](https://github.com/Unidata/netcdf-c/pull/2032).
* [Bug Fix] Fix dimension_separator bug in libnczarr. See [Github #2035](https://github.com/Unidata/netcdf-c/pull/2035).
* [Bug Fix] Fix bugs in libdap4. See [Github #2005](https://github.com/Unidata/netcdf-c/pull/2005).
* [Bug Fix] Store NCZarr fillvalue as a singleton instead of a 1-element array. See [Github #2017](https://github.com/Unidata/netcdf-c/pull/2017).
* [Bug Fixes] The netcdf-c library was incorrectly determining the scope of dimension; similar to the type scope problem. See [Github #2012](https://github.com/Unidata/netcdf-c/pull/2012) for more information.
* [Bug Fix] Fix bug with windows version of mkstemp that causes failure to create more than 26 temp files. See [Github #1998](https://github.com/Unidata/netcdf-c/pull/1998).
* [Bug Fixes] The netcdf-c library was incorrectly determining the scope of types referred to by nc_inq_type_equal. See [Github #1959](https://github.com/Unidata/netcdf-c/pull/1959) for more information.
* [Enhancement] Improve the error reporting when attempting to use a filter for which no implementation can be found in HDF5_PLUGIN_PATH. See [Github #2000](https://github.com/Unidata/netcdf-c/pull/2000) for more information.
* [Bug Fix] Fix bug in ncdump that assumes that there is a relationship between the total number of dimensions and the max dimension id. See [Github #2004](https://github.com/Unidata/netcdf-c/issues/2004).
* [Enhancement] Add support for the new "dimension_separator" enhancement to Zarr v2. See [Github #1990](https://github.com/Unidata/netcdf-c/pull/1990) for more information.
* [Bug Fix] Fix hack for handling failure of shell programs to properly handle escape characters. See [Github #1989](https://github.com/Unidata/netcdf-c/issues/1989).
* [Bug Fix] Allow some primitive type names to be used as identifiers depending on the file format. See [Github #1984](https://github.com/Unidata/netcdf-c/issues/1984).
* [Enhancement] Add support for reading/writing pure Zarr storage format that supports the XArray _ARRAY_DIMENSIONS attribute. See [Github #1952](https://github.com/Unidata/netcdf-c/pull/1952) for more information.
* [Update] Updated version of bzip2 used in filter testing/functionality, in support of [Github #1969](https://github.com/Unidata/netcdf-c/issues/1969).
* [Enhancement] Bump the NC_DISPATCH_VERSION from 2 to 3, and as a side effect, unify the definition of NC_DISPATCH_VERSION so it only needs to be defined in CMakeLists.txt and configure.ac. See [Github #1945](https://github.com/Unidata/netcdf-c/pull/1945) for more information.
* [Enhancement] Provide better cross platform path name management. This converts paths for various platforms (e.g. Windows, MSYS, etc.) so that they are in the proper format for the executing platform. See [Github #1958](https://github.com/Unidata/netcdf-c/pull/1958) for more information.
* [Bug Fixes] The nccopy program was treating -d0 as turning deflation on rather than interpreting it as "turn off deflation". See [Github #1944](https://github.com/Unidata/netcdf-c/pull/1944) for more information.
* [Enhancement] Add support for storing NCZarr data in zip files. See [Github #1942](https://github.com/Unidata/netcdf-c/pull/1942) for more information.
* [Bug Fixes] Fix some memory leaks in NCZarr, fix a bug with long strides in NCZarr. See [Github #1913](https://github.com/Unidata/netcdf-c/pull/1913) for more information.
* [Enhancement] Add some optimizations to NCZarr, dosome cleanup of code cruft, add some NCZarr test cases, add a performance test to NCZarr. See [Github #1908](https://github.com/Unidata/netcdf-c/pull/1908) for more information.
* [Bug Fix] Implement a better chunk cache system for NCZarr. The cache now uses extendible hashing plus a linked list for provide a combination of expandibility, fast access, and LRU behavior. See [Github #1887](https://github.com/Unidata/netcdf-c/pull/1887) for more information.
* [Enhancement] Provide .rc fields for S3 authentication: HTTP.S3.ACCESSID and HTTP.S3.SECRETKEY.
* [Enhancement] Give the client control over what parts of a DAP2 URL are URL encoded (i.e. %xx). This is to support the different decoding rules that servers apply to incoming URLS. See [Github #1884](https://github.com/Unidata/netcdf-c/pull/1844) for more information.
* [Bug Fix] Fix incorrect time offsets from `ncdump -t`, in some cases when the time `units` attribute contains both a **non-zero** time-of-day, and a time zone suffix containing the letter "T", such as "UTC". See [Github #1866](https://github.com/Unidata/netcdf-c/pull/1866) for more information.
* [Bug Fix] Support aligned access for selected ARM processors. See [Github #1871](https://github.com/Unidata/netcdf-c/pull/1871) for more information.
* [Bug Fix] Revert the internal filter code to simplify it. From the user's point of view, the only visible change should be that (1) the functions that convert text to filter specs have had their signature reverted and renamed and have been moved to netcdf_aux.h, and (2) Some filter API functions now return NC_ENOFILTER when inquiry is made about some filter. Internally, the dispatch table has been modified to get rid of the complex structures.
* [Bug Fix] If the HDF5 byte-range Virtual File Driver is available )HDf5 1.10.6 or later) then use it because it has better performance than the one currently built into the netcdf library.
* [Enhancement] Added new test for using compression with parallel I/O: nc_test4/tst_h_par_compress.c. See [https://github.com/Unidata/netcdf-c/pull/1784].
* [Bug Fix] Don't return error for extra calls to nc_redef() for netCDF/HDF5 files, unless classic model is in use. See [https://github.com/Unidata/netcdf-c/issues/1779].
* [Enhancement] Added new parallel I/O benchmark program to mimic NOAA UFS data writes, built when --enable-benchmarks is in configure. See [https://github.com/Unidata/netcdf-c/pull/1777].
* [Enhancement] Add support for cloud storage using a variant of the Zarr storage format. Warning: this feature is highly experimental and is subject to rapid evolution [https://www.unidata.ucar.edu/blogs/developer/en/entry/overview-of-zarr-support-in].
* [Bug Fix] Fix nccopy to properly set default chunking parameters when not otherwise specified. This can significantly improve performance in selected cases. Note that if seeing slow performance with nccopy, then, as a work-around, specifically set the chunking parameters. [https://github.com/Unidata/netcdf-c/issues/1763].
* [Bug Fix] Fix some protocol bugs/differences between the netcdf-c library and the OPeNDAP Hyrax server. Also cleanup checksum handling [https://github.com/Unidata/netcdf-c/issues/1712].* [Bug Fix] IMPORTANT: Ncgen was not properly handling large
* [Bug Fix] Now larger cache settings are used for sequential HDF5 file creates/opens on parallel I/O capable builds; see [Github #1716](https://github.com/Unidata/netcdf-c/issues/1716) for more information.
* [Bug Fix] Fixed a scalar annotation error when scalar == 0; see [Github #1707](https://github.com/Unidata/netcdf-c/issues/1707) for more information.
* [Bug Fix] Use proper CURLOPT values for VERIFYHOST and VERIFYPEER; the semantics for VERIFYHOST in particular changed. Documented in NUG/DAP2.md. See [https://github.com/Unidata/netcdf-c/issues/1684].
* [Bug Fix] Now allow nc_inq_var_deflate()/nc_inq_var_szip() to be called for all formats, not just HDF5. Non-HDF5 files return NC_NOERR and report no compression in use. This reverts behavior that was changed in the 4.7.4 release. See [https://github.com/Unidata/netcdf-c/issues/1691].
* [Bug Fix] Correct behavior for the command line utilities when directly accessing a directory using utf8 characters. See [Github #1669](https://github.com/Unidata/netcdf-c/issues/1669), [Github #1668](https://github.com/Unidata/netcdf-c/issues/1668) and [Github #1666](https://github.com/Unidata/netcdf-c/issues/1666) for more information.
* [Bug Fix] Attempts to set filters or chunked storage on scalar vars will now return NC_EINVAL. Scalar vars cannot be chunked, and only chunked vars can have filters. Previously the library ignored these attempts, and always storing scalars as contiguous storage. See [https://github.com/Unidata/netcdf-c/issues/1644].
* [Enhancement] Now nc_inq_var_szip retuns 0 for parameter values if szip is not in use for var. See [https://github.com/Unidata/netcdf-c/issues/1618].
* [Enhancement] Now allow parallel I/O with filters, for HDF5-1.10.3 and later. See [https://github.com/Unidata/netcdf-c/issues/1473].
* [Enhancement] Increased default size of cache buffer to 16 MB, from 4 MB. Increased number of slots to 4133. See [https://github.com/Unidata/netcdf-c/issues/1541].
* [Enhancement] Allow zlib compression to be used with parallel I/O writes, if HDF5 version is 1.10.3 or greater. See [https://github.com/Unidata/netcdf-c/issues/1580].
* [Enhancement] Restore use of szip compression when writing data (including writing in parallel if HDF5 version is 1.10.3 or greater). See [https://github.com/Unidata/netcdf-c/issues/1546].
* [Enhancement] Enable use of compact storage option for small vars in netCDF/HDF5 files. See [https://github.com/Unidata/netcdf-c/issues/1570].
* [Enhancement] Updated benchmarking program bm_file.c to better handle very large files. See [https://github.com/Unidata/netcdf-c/issues/1555].
* [Enhancement] Added version number to dispatch table, and now check version with nc_def_user_format(). See [https://github.com/Unidata/netcdf-c/issues/1599].
* [Bug Fix] Fixed user setting of MPI launcher for parallel I/O HDF5 test in h5_test. See [https://github.com/Unidata/netcdf-c/issues/1626].
* [Bug Fix] Fixed problem of growing memory when netCDF-4 files were opened and closed. See [https://github.com/Unidata/netcdf-c/issues/1575 and https://github.com/Unidata/netcdf-c/issues/1571].
* [Bug Fix] Library was modified so that rewriting the same attribute happens without deleting the attribute, to avoid a limit on how many times this may be done in HDF5. This fix was thought to be in 4.6.2 but was not. See [https://github.com/Unidata/netcdf-c/issues/350].
* [Enhancement] Add a dispatch version number to netcdf_meta.h and libnetcdf.settings, in case we decide to change dispatch table in future. See [https://github.com/Unidata/netcdf-c/issues/1469].
* [Bug Fix] Now testing that endianness can only be set on atomic ints and floats. See [https://github.com/Unidata/netcdf-c/issues/1479].
* [Bug Fix] Fix for subtle error involving var and unlimited dim of the same name, but unrelated, in netCDF-4. See [https://github.com/Unidata/netcdf-c/issues/1496].
* [Enhancement] Update for attribute documentation. See [https://github.com/Unidata/netcdf-c/issues/1512].
* [Bug Fix][Enhancement] Corrected assignment of anonymous (a.k.a. phony) dimensions in an HDF5 file. Now when a dataset uses multiple dimensions of the same size, netcdf assumes they are different dimensions. See [GitHub #1484](https://github.com/Unidata/netcdf-c/issues/1484) for more information.
* [Bug Fix][Enhancement] Corrected an issue where protected memory was being written to with some pointer slight-of-hand. This has been in the code for a while, but appears to be caught by the compiler on OSX, under circumstances yet to be completely nailed down. See [GitHub #1486](https://github.com/Unidata/netcdf-c/issues/1486) for more information.
* [Enhancement] [Parallel IO] Added support for parallel functions in MSVC. See [Github #1492](https://github.com/Unidata/netcdf-c/pull/1492) for more information.
* [Enhancement] Added a function for changing the ncid of an open file. This function should only be used if you know what you are doing, and is meant to be used primarily with PIO integration. See [GitHub #1483](https://github.com/Unidata/netcdf-c/pull/1483) and [GitHub #1487](https://github.com/Unidata/netcdf-c/pull/1487) for more information.
* [Enhancement] Added unit_test directory, which contains unit tests for the libdispatch and libsrc4 code (and any other directories that want to put unit tests there). Use --disable-unit-tests to run without unit tests (ex. for code coverage analysis). See [GitHub #1458](https://github.com/Unidata/netcdf-c/issues/1458).
* [Bug Fix] Remove obsolete _CRAYMPP and LOCKNUMREC macros from code. Also brought documentation up to date in man page. These macros were used in ancient times, before modern parallel I/O systems were developed. Programmers interested in parallel I/O should see nc_open_par() and nc_create_par(). See [GitHub #1459](https://github.com/Unidata/netcdf-c/issues/1459).
* [Enhancement] Remove obsolete and deprecated functions nc_set_base_pe() and nc_inq_base_pe() from the dispatch table. (Both functions are still supported in the library, this is an internal change only.) See [GitHub #1468](https://github.com/Unidata/netcdf-c/issues/1468).
* [Bug Fix] Reverted nccopy behavior so that if no -c parameters are given, then any default chunking is left to the netcdf-c library to decide. See [GitHub #1436](https://github.com/Unidata/netcdf-c/issues/1436).
* [Enhancement] Updated behavior of `pkgconfig` and `nc-config` to allow the use of the `--static` flags, e.g. `nc-config --libs --static`, which will show information for linking against `libnetcdf` statically. See [Github #1360](https://github.com/Unidata/netcdf-c/issues/1360) and [Github #1257](https://github.com/Unidata/netcdf-c/issues/1257) for more information.
* Update the license from the home-brewed NetCDF license to the standard 3-Clause BSD License. This change does not result in any new restrictions; it is merely the adoption of a standard, well-known and well-understood license in place of the historic NetCDF license written at Unidata. This is part of a broader push by Unidata to adopt modern, standardized licensing.
* [Bug Fix] Correctly generated `netcdf.pc` generated either by `configure` or `cmake`. If linking against a static netcdf, you would need to pass the `--static` argument to `pkg-config` in order to list all of the downstream dependencies. See [Github #1324](https://github.com/Unidata/netcdf-c/issues/1324) for more information.
* Now always write hidden coordinates attribute, which allows faster file opens when present. See [Github #1262](https://github.com/Unidata/netcdf-c/issues/1262) for more information.
* Some fixes for rename, including fix for renumbering of varids after a rename (#1307), renaming var to dim without coordinate var. See [Github #1297](https://github.com/Unidata/netcdf-c/issues/1297).
* Fix of NULL parameter causing segfaults in put_vars functions. See [Github #1265](https://github.com/Unidata/netcdf-c/issues/1265) for more information.
* Fix of --enable-benchmark benchmark tests [Github #1211](https://github.com/Unidata/netcdf-c/issues/1211)
* Update the license from the home-brewed NetCDF license to the standard 3-Clause BSD License. This change does not result in any new restrictions; it is merely the adoption of a standard, well-known and well-understood license in place of the historic NetCDF license written at Unidata. This is part of a broader push by Unidata to adopt modern, standardized licensing.
* [BugFix] Corrected DAP-releated issues on big-endian machines. See [Github #1321](https://github.com/Unidata/netcdf-c/issues/1321), [Github #1302](https://github.com/Unidata/netcdf-c/issues/1302) for more information.
* [BugFix][Enhancement] Various and sundry bugfixes and performance enhancements, thanks to \@edhartnett, \@gsjaardema, \@t-b, \@wkliao, and all of our other contributors.
* [Enhancement] Extended `nccopy -F` syntax to support multiple variables with a single invocation. See [Github #1311](https://github.com/Unidata/netcdf-c/issues/1311) for more information.
* [BugFix] Corrected an issue where DAP2 was incorrectly converting signed bytes, resulting in an erroneous error message under some circumstances. See [GitHub #1317](https://github.com/Unidata/netcdf-c/issues/1317) for more information. See [Github #1319](https://github.com/Unidata/netcdf-c/issues/1319) for related information.
* [BugFix][Enhancement] Modified `nccopy` so that `_NCProperties` is not copied over verbatim but is instead generated based on the version of `libnetcdf` used when copying the file. Additionally, `_NCProperties` are displayed if/when associated with a netcdf3 file, now. See [GitHub #803](https://github.com/Unidata/netcdf-c/issues/803) for more information.
* [Enhancement] Lazy att read - only read atts when user requests one of them. See [GitHub #857](https://github.com/Unidata/netcdf-c/issues/857).
* [Enhancement] Fast global att read - when global atts are read, they are read much more quickly. See [GitHub #857](https://github.com/Unidata/netcdf-c/issues/857).
* [Enhancement] Add nccopy command options for per-variable chunk sizing, and minimum chunk size. See [GitHub #1087](https://github.com/Unidata/netcdf-c/pull/1087).
* [Bug Fix] Fix nccopy handling of user specified chunk sizes. See [GitHub #725](https://github.com/Unidata/netcdf-c/issues/725),[#1087](https://github.com/Unidata/netcdf-c/issues/1087).
* [Bug Fix] Avoid limit on number of times a netCDF4 attribute can be updated. Not a complete fix for the HDF5 "maximum creation order" problem, but should greatly reduce occurrences in many real-world cases. See [GitHub #350](https://github.com/Unidata/netcdf-c/issues/350).
* [Bug Fix] The use of NC_DISKLESS has been modified to make it cleaner. This adds a new flag called NC_PERSIST that takes over the now obsolete NC_MPIPOSIX.
* [Bug Fix] When using filters with HDF5 1.10.x or later, it is necessary to utilize the HDF5 replacements for malloc, realloc, and free in the filter code.
* [Enhancement] Create a new version of _NCProperties provenance attribute. This version (version 2) supports arbitrary key-value pairs. It is the default when new files are created. Version 1 continues to be accepted.
* [Enhancement] Allow user to set http read buffersize for DAP2 and DAP4 using the tag HTTP.READ.BUFFERSIZE in the .daprc file.
* [Enhancement] Allow user to set http keepalive for DAP2 and DAP4 using the tag HTTP.KEEPALIVE in the .daprc file (see the OPeNDAP documentation for details).
* [Enhancement] Improved the performance of the nc_get/put_vars operations by using the equivalent slab capabilities of hdf5. Result is a significant speedup of these operations. See [GitHub #1001](https://github.com/Unidata/netcdf-c/pull/1001) for more information.
* [Enhancement] Expanded the capabilities of `NC_INMEMORY` to support writing and accessing the final modified memory. See [GitHub #879](https://github.com/Unidata/netcdf-c/pull/879) for more information.
* [Bug Fix] Corrected a number of memory issues identified in `ncgen`. See [GitHub #558 for more information](https://github.com/Unidata/netcdf-c/pull/558).
* [Bug Fix] Corrected an issue which could result in a dap4 failure. See [Github #888](https://github.com/Unidata/netcdf-c/pull/888) for more information.
* [Bug Fix][Enhancement] Allow `nccopy` to control output filter suppresion. See [Github #894](https://github.com/Unidata/netcdf-c/pull/894) for more information.
* [Enhancement] Reverted some new behaviors that, while in line with the netCDF specification, broke existing workflows. See [Github #843](https://github.com/Unidata/netcdf-c/issues/843) for more information.
* [Bug Fix] Improved support for CRT builds with Visual Studio, improves zlib detection in hdf5 library. See [Github #853](https://github.com/Unidata/netcdf-c/pull/853) for more information.
* [Enhancement][Internal] Moved HDF4 into a distinct dispatch layer. See [Github #849](https://github.com/Unidata/netcdf-c/pull/849) for more information.
* [Enhancement] Added an option to enable strict null-byte padding for headers; this padding was specified in the spec but was not enforced. Enabling this option will allow you to check your files, as it will return an E_NULLPAD error. It is possible for these files to have been written by older versions of libnetcdf. There is no effective problem caused by this lack of null padding, so enabling these options is informational only. The options for `configure` and `cmake` are `--enable-strict-null-byte-header-padding` and `-DENABLE_STRICT_NULL_BYTE_HEADER_PADDING`, respectively. See [Github #657](https://github.com/Unidata/netcdf-c/issues/657) for more information.
* [Enhancement] Reverted behavior/handling of out-of-range attribute values to pre-4.5.0 default. See [Github #512](https://github.com/Unidata/netcdf-c/issues/512) for more information.
* [Bug] Fixed error in tst_parallel2.c. See [Github #545](https://github.com/Unidata/netcdf-c/issues/545) for more information.
* [Bug] Fixed handling of corrupt files + proper offset handling for hdf5 files. See [Github #552](https://github.com/Unidata/netcdf-c/issues/552) for more information.
* [Bug] Corrected a memory overflow in `tst_h_dimscales`, see [Github #511](https://github.com/Unidata/netcdf-c/issues/511), [Github #505](https://github.com/Unidata/netcdf-c/issues/505), [Github #363](https://github.com/Unidata/netcdf-c/issues/363) and [Github #244](https://github.com/Unidata/netcdf-c/issues/244) for more information.
* Corrected an issue which could potential result in a hang while using parallel file I/O. See [Github #449](https://github.com/Unidata/netcdf-c/pull/449) for more information.
* Addressed an issue with `ncdump` not properly handling dates on a 366 day calendar. See [GitHub #359](https://github.com/Unidata/netcdf-c/issues/359) for more information.
* [Update] Due to ongoing issues, native CDF5 support has been disabled by **default**. You can use the options mentioned below (`--enable-cdf5` or `-DENABLE_CDF5=TRUE` for `configure` or `cmake`, respectively). Just be aware that for the time being, Reading/Writing CDF5 files on 32-bit platforms may result in unexpected behavior when using extremely large variables. For 32-bit platforms it is best to continue using `NC_FORMAT_64BIT_OFFSET`.
* [Bug] Corrected an issue where older versions of curl might fail. See [GitHub #487](https://github.com/Unidata/netcdf-c/issues/487) for more information.
* [Enhancement] Added options to enable/disable `CDF5` support at configure time for autotools and cmake-based builds. The options are `--enable/disable-cdf5` and `ENABLE_CDF5`, respectively. See [Github #484](https://github.com/Unidata/netcdf-c/issues/484) for more information.
* [Bug Fix] Corrected an issue when subsetting a netcdf3 file via `nccopy -v/-V`. See [Github #425](https://github.com/Unidata/netcdf-c/issues/425) and [Github #463](https://github.com/Unidata/netcdf-c/issues/463) for more information.
* [Bug Fix] Corrected `--has-dap` and `--has-dap4` output for cmake-based builds. See [GitHub #473](https://github.com/Unidata/netcdf-c/pull/473) for more information.
* [Bug Fix] Corrected an issue where `NC_64BIT_DATA` files were being read incorrectly by ncdump, despite the data having been written correctly. See [GitHub #457](https://github.com/Unidata/netcdf-c/issues/457) for more information.
* [Bug Fix] Addressed an issue with how cmake was implementing large file support on 32-bit systems. See [GitHub #385](https://github.com/Unidata/netcdf-c/issues/385) for more information.
* [Bug Fix] Addressed an issue where ncgen would not respect keyword case. See [GitHub #310](https://github.com/Unidata/netcdf-c/issues/310) for more information.
* [Enhancement] The remote testing server can now be specified with the `--with-testserver` option to ./configure.
* [Enhancement] Modified netCDF4 to use ASCII for NC_CHAR. See [Github Pull request #316](https://github.com/Unidata/netcdf-c/pull/316) for more information.
* [Bug Fix] Corrected an error with how dimsizes might be read. See [Github #410](https://github.com/unidata/netcdf-c/issues/410) for more information.
* [Bug Fix] Corrected an issue where 'make check' would fail if 'make' or 'make all' had not run first. See [Github #339](https://github.com/Unidata/netcdf-c/issues/339) for more information.
* [Bug Fix] Corrected an issue on Windows with Large file tests. See [Github #385](https://github.com/Unidata/netcdf-c/issues/385]) for more information.
* [Bug Fix] Corrected an issue with diskless file access, see [Pull Request #400](https://github.com/Unidata/netcdf-c/issues/400) and [Pull Request #403](https://github.com/Unidata/netcdf-c/issues/403) for more information.
* [Refactor] the oc2 library is no longer independent of the main netcdf-c library. For example, it now uses ncuri, nclist, and ncbytes instead of its homegrown equivalents.
* [Bug Fix] `NC_EGLOBAL` is now properly returned when attempting to set a global `_FillValue` attribute. See [GitHub #388](https://github.com/Unidata/netcdf-c/issues/388) and [GitHub #389](https://github.com/Unidata/netcdf-c/issues/389) for more information.
* [Bug Fix] Corrected an issue where data loss would occur when `_FillValue` was mistakenly allowed to be redefined. See [Github #390](https://github.com/Unidata/netcdf-c/issues/390), [GitHub #387](https://github.com/Unidata/netcdf-c/pull/387) for more information.
* [Upgrade][Bug] Corrected an issue regarding how "orphaned" DAS attributes were handled. See [GitHub #376](https://github.com/Unidata/netcdf-c/pull/376) for more information.
* [Upgrade] Update utf8proc.[ch] to use the version now maintained by the Julia Language project (https://github.com/JuliaLang/utf8proc/blob/master/LICENSE.md).
* [Bug] Addressed conversion problem with Windows sscanf. This primarily affected some OPeNDAP URLs on Windows. See [GitHub #365](https://github.com/Unidata/netcdf-c/issues/365) and [GitHub #366](https://github.com/Unidata/netcdf-c/issues/366) for more information.
* [Enhancement] Added support for HDF5 collective metadata operations when available. Patch submitted by Greg Sjaardema, see [Pull request #335](https://github.com/Unidata/netcdf-c/pull/335) for more information.
* [Bug] Addressed an issue where netCDF wouldn't build on Windows systems using MSVC 2012. See [GitHub #304](https://github.com/Unidata/netcdf-c/issues/304) for more information.
* [Enhancement] Incorporated an enhancement provided by Greg Sjaardema, which may improve read/write times for some complex files. Basically, linked lists were replaced in some locations where it was safe to use an array/table. See [Pull request #328](https://github.com/Unidata/netcdf-c/pull/328) for more information.
* [Bug] Fixed an issue where `ncgen` would potentially crash or write incorrect netCDF4 binary data under very specific circumstances. This bug did *not* affect data written on 32-bit systems or by using the netCDF library; it was specific to `ncgen`. This would only happen when writing a compound data type containing an 8-byte data type followed by a 4-byte data type *and* the 4-byte data type was not properly aligned; this would *possibly* result in incorrect padding. This did not affect 32-bit systems, or data written directly by the library. See [GitHub #323](https://github.com/Unidata/netcdf-c/issues/323) for more information.
* [Documentation] Updated documentation related to netCDF variable names and DAP2 access to reflect the undefined behavior potentially observed when DAP2 reserved keywords are used as netCDF variable names. See [GitHub #308](https://github.com/Unidata/netcdf-c/issues/308) for more information.
* [Bug] Fixed an issue with `nc_inq_type()` not returning proper value in some circumstances. See [GitHub #317](https://github.com/Unidata/netcdf-c/issues/317) for more information.
* [Bug] Corrected an issue related to test failures when `--disable-utilities` or `-DENABLE_UTILITIES=OFF` are specified when building with autotools or cmake, respectively. See [GitHub #313](https://github.com/Unidata/netcdf-c/issues/313) for more information.
* [Bug][Enhancement] Corrected a behavioral issue with the `_NCProperties` attribute taking up too much space. See [GitHub #300](https://github.com/Unidata/netcdf-c/issues/300) and [GitHub #301](https://github.com/Unidata/netcdf-c/pull/301) for more information.
* [Bug] Corrected behavior for `nc-config` so that, if `nf-config` is found in system, the proper fortran-related information will be conveyed. See [GitHub #296](https://github.com/Unidata/netcdf-c/issues/296] for more information.
* [File Change] Starting with release 4.4.1, netCDF-4 files created will have superblock version 0 instead of superblock version 2, as was observed in previous netCDF versions. This is due to a workaround required to avoid backwards binary incompatibility when using libhdf5 1.10.x or greater. Superblock versions 0 and 2 appear to be forward and backward compatible. Other than a different superblock number the data should remain consistent.
* [Enhancement] Added better error reporting when ncdump/nccopy are given a bad constraint in a DAP url. See [GitHub #279](https://github.com/Unidata/netcdf-c/pull/279) for more information.
* [Bug Fix] Corrected an issue where adding a \_FillValue attribute to a variable would result in other attributes being lost. See [GitHub #239](https://github.com/Unidata/netcdf-c/issues/239) for more details.
* [Enhancement] Added provenance information to files created. This information consists of a persistent attribute named `_NCProperties` plus two computed attributes, `_IsNetcdf4` and `_SuperblockVersion`. Associated documentation was added to the file `docs/attribute_conventions.md`. See [GitHub pull request #260](https://github.com/Unidata/netcdf-c/pull/260) for more information.
* [Bug Fix] Cleaned up some dead links in the doxygen-generated documentation.
* [Bug Fix] Corrected several issues related to building under Visual Studio 2014.
* [Bug Fix] Corrected several test failures related to HDF5 `1.10.0`
* [Bug Fix] Reverted SOVersion *current* to 11 from 12; it was incorrectly incremented in netCDF-C release 4.4.1-RC1.
* [Bug Fix][Enhancement] Fixed an issue with netCDF4 files generated using version `1.10.0` of the HDF5 library. The 1.10 release potentially changed the underlying file format, introducing a backwards compatibility issue with the files generated. HDF5 provided an API for retaining the 1.8.x file format, which is now on by default. See [GitHub Issue #250](https://github.com/Unidata/netcdf-c/issues/250) for more information.
* [Bug Fix] Corrected an issue with autotools-based builds performed out-of-source-tree. See [GitHub Issue #242](https://github.com/Unidata/netcdf-c/issues/242) for more information.
* [Enhancement] Modified `nc_inq_type()` so that it would work more broadly without requiring a valid ncid. See [GitHub Issue #240](https://github.com/Unidata/netcdf-c/issues/240) for more information.
* [Enhancement] Accepted a patch code which added a hashmap lookup for rapid var and dim retrieval in nc3 files, contributed by Greg Sjaardema. See [GitHub Pull Request #238](https://github.com/Unidata/netcdf-c/pull/238) for more information.
* [Bug Fix] Accepted a contributed pull request which corrected an issue with how the cmake-generated `nc-config` file determined the location of installed files. See [GitHub Pull Request #235](https://github.com/Unidata/netcdf-c/pull/235) for more information.
* [Enhancement] Added an advanced option for CMake-based builds, `ENABLE_SHARED_LIBRARY_VERSION`. This option is `ON` by default, but if turned off, only `libnetcdf.dylib` will be generated, instead of files containing the SOVERSION in the file name. This is a requested feature most people might not care about. See [GitHub #228](https://github.com/Unidata/netcdf-c/issues/228) for more information.
* [Bug Fix] Corrected an issue with duplicated error codes defined in multiple header files. See [GitHub #213](https://github.com/Unidata/netcdf-c/issues/213) for more information.
* [Bug Fix] Addressed an issue specific to Visual Studio 2015 on Windows. On very large files, some calls to the `fstat` class of functions would fail for no apparent reason. This behavior was **not** observed under Visual Studio 2013. This has now been mitigated. See [GitHub #188](https://github.com/Unidata/netcdf-c/issues/188) for more information.
* [Enhancement] Updated `nc-config` to report whether `logging` is enabled in netcdf. Additionally, if `f03` is available in an installed netcdf-fortran library, it will now be reported as well.
* [Bug Fix] Addressed an issue where `netcdf_mem.h` was not being installed by cmake. See [GitHub #227](https://github.com/Unidata/netcdf-c/issues/227) for more information.
* [Bug Fix] Addressed an issue where `ncdump` would crash when trying to read a netcdf file containing an empty ragged `VLEN` variable in an unlimited dimension. See [GitHub #221](https://github.com/Unidata/netcdf-c/issues/221) for more information.
* Modified `CMakeLists.txt` to work with the re-organized cmake configuration used by the latest HDF5, `1.8.16`, on Windows. Before this fix, netCDF would fail to locate hdf5 1.8.16 when using cmake on Windows. See [GitHub #186](https://github.com/Unidata/netcdf-c/issues/186) for more information.
* Addressed an issue with `ncdump` when annotations were used. The indices for the last row suffered from an off-by-1 error. See [GitHub issue #181](https://github.com/Unidata/netcdf-c/issues/181) for more information.
* Addressed an issue on platforms where `char` is `unsigned` by default (such as `ARM`), as well as an issue describing regarding undefined behavior, again on `ARM`. See [GitHub issue #159](https://github.com/Unidata/netcdf-c/issues/159) for detailed information.
* Updated documentation for `nc_get_att_string()` to reflect the fact that it returns allocated memory which must be explicitly free'd using `nc_free_string()`. Reported by Constantine Khroulev, see [GitHub Issue 171](https://github.com/Unidata/netcdf-c/issues/171) for more information.
* Updated documentation to reference the new `NodeJS` interface to netcdf4, by Sven Willner. It is available from [https://www.npmjs.com/package/netcdf4](https://www.npmjs.com/package/netcdf4) or from the GitHub repository at [https://github.com/swillner/netcdf4-js](https://github.com/swillner/netcdf4-js).
* Incorporated pull request https://github.com/Unidata/netcdf-c/pull/150 from Greg Sjaardema to remove the internal hard-wired use of `NC_MAX_DIMS`, instead using a dynamic memory allocation.
* Added a fix for https://github.com/Unidata/netcdf-c/issues/149, which was reported several times in quick succession within an hour of the RC4 release.
The various extended format flags of the format `NC_FORMAT_FOO` have been refactored into the form `NC_FORMATX_FOO`. The old flags still exist but have been marked as deprecated and will be removed at some point. This was done to avoid confusion between the extended format flags and the format flags `NC_FORMAT_CLASSIC`, `NC_FORMAT_64BIT_OFFSET`, etc. The mapping of deprecated-to-new flags is as follows:
* Reduced minimum cmake version to `2.8.11` from `2.8.12`. This will allow for cmake use on a broader set of popular linux platforms without having to do a custom cmake install. See https://github.com/Unidata/netcdf-c/issues/135 for more information.
* The documentation section `The Default Chunking Scheme` has been updated with more information. This lives in the `guide.dox` file in the `docs/` directory, or can be found online in the appropriate location (typically http://www.unidata.ucar.edu/netcdf/docs/), once this release has been published.
* Addressed an inefficiency in how bytes would be swapped when converting between `LITTLE` and `BIG` ENDIANNESS. See [NCF-338](https://bugtracking.unidata.ucar.edu/browse/NCF-338) for more information.
* Addressed an issue where an interrupted read on a `POSIX` system would return an error even if errno had been properly set to `EINTR`. This issue was initially reported by David Knaak at Cray. More information may be found at [NCF-337](https://bugtracking.unidata.ucar.edu/browse/NCF-337).
* The pre-built Windows binaries are now built using `Visual Studio 2012`, instead of `Visual Studio 2010`. Source-code compilation remains function with `Visual Studio 2010`, this is just a change in the pre-built binaries.
* Added support for opening in-memory file content. See `include/netcdf_mem.h` for the procedure signature. Basically, it allows one to fill a chunk of memory with the equivalent of some netCDF file and then open it and read from it as if it were any other file. See [NCF-328](https://bugtracking.unidata.ucar.edu/browse/NCF-328) for more information.
* Addressed an issue when reading hdf4 files with explicit little-endian datatypes. This issue was [reported by Tim Burgess at GitHub](https://github.com/Unidata/netcdf-c/issues/113). See [NCF-332](https://bugtracking.unidata.ucar.edu/browse/NCF-332) for more information.
* Addressed an issue with IBM's `XL C` compiler on AIX and how it handled some calls to malloc. Also, as suggested by Wolfgang Hayek, developers using this compiler may need to pass `CPPFLAGS=-D_LINUX_SOURCE_COMPAT` to avoid some test failures.
* Addressed an issure in netcdf4 related to specifying an endianness explicitly. When specifying an endianness for `NC_FLOAT`, the value would appear to not be written to file, if checked with `ncdump -s`. The issue was more subtle; the value would be written but was not being read from file properly for non-`NC_INT`. See [GitHub Issue](https://github.com/Unidata/netcdf-c/issues/112) or [NCF-331](https://bugtracking.unidata.ucar.edu/browse/NCF-331) for more information.
* Addressed an issue in netcdf4 on Windows w/DAP related to how byte values were copied with sscanf. Issue originally reported by Ellen Johnson at Mathworks, see [NCF-330](https://bugtracking.unidata.ucar.edu/browse/NCF-330) for more information.
* Addressed in issue in netcdf4 files on Windows, built with Microsoft Visual Studio, which could result in a memory leak. See [NCF-329](https://bugtracking.unidata.ucar.edu/browse/NCF-329) for more information.
* Addressed an issue in netcdf4 files where writing unlimited dimensions that were not declared at head of the dimensions list, as reported by Ellen Johnson at Mathworks. See [NCF-326](https://bugtracking.unidata.ucar.edu/browse/NCF-326) for more information.
* Fixed a bug related to renaming the attributes of coordinate variables in a subgroup. See [NCF-325](https://bugtracking.unidata.ucar.edu/browse/NCF-325) for more information.
* Fixed bug resulting in error closing a valid netCDF-4 file with a dimension and a non-coordinate variable with the same name. [NCF-324](https://bugtracking.unidata.ucar.edu/browse/NCF-324)
* Added functionality to make it easier to build `netcdf-fortran` as part of the `netcdf-c` build for *NON-MSVC* builds. This functionality is enabled at configure time by using the following **Highly Experimental** options:
> These make targets are **only** valid after `make install` has been invoked. This cannot be enforced rigidly in the makefile for reasons we will expand on in the documentation, but in short: `make install` may require sudo, but using sudo will discard environmental variables required when attempting to build netcdf-fortran in this manner.<br><br>
> It is important to note that this is functionality is for *convenience only*. It will remain possible to build `netcdf-c` and `netcdf-fortran` manually. These make targets should hopefully suffice for the majority of our users, but for corner cases it may still be required of the user to perform a manual build. [NCF-323](https://bugtracking.unidata.ucar.edu/browse/NCF-323)
* Added a failure state if the `m4` utility is not found on non-Windows systems; previously, the build would fail when it reached the point of invoking m4.
* Added an explicit check in the build systems (autotools, cmake) for the CURL-related option `CURLOPT_CHUNK_BGN_FUNCTION`. This option was introduced in libcurl version `7.21.0`. On installations which require libcurl and have this version, `CURLOPT_CHUNK_BGN_FUNCTION` will be available. Otherwise, it will not.
* The PnetCDF support was not properly being used to provide mpi parallel io for netcdf-3 classic files. The wrong dispatch table was being used. [NCF-319](https://bugtracking.unidata.ucar.edu/browse/NCF-319)
* In nccopy utility, provided proper default for unlimited dimension in chunk-size specification instead of requiring explicit chunk size. Added associated test. [NCF-321](https://bugtracking.unidata.ucar.edu/browse/NCF-321)
* Fixed documentation typo in FILL_DOUBLE definition in classic format specification grammar. Fixed other typos and inconsistencies in Doxygen version of User Guide.
* For nccopy and ncgen, added numeric options (-3, -4, -6, -7) for output format, to provide less confusing format version specifications than the error-prone equivalent -k options (-k1, -k2, -k3, -k4). The new numeric options are compatible with NCO's mnemonic version options. The old -k numeric options will still be accepted but are deprecated, due to easy confusion between format numbers and format names. [NCF-314](https://bugtracking.unidata.ucar.edu/browse/NCF-314)
* Fixed bug in ncgen. When classic format was in force (k=1 or k=4), the "long" datatype should be treated as int32. Was returning an error. [NCF-318](https://bugtracking.unidata.ucar.edu/browse/NCF-318)
* Fixed bug where if the netCDF-C library is built with the HDF5 library but without the HDF4 library and one attempts to open an HDF4 file, an abort occurs rather than returning a proper error code (NC_ENOTNC). [NCF-317](https://bugtracking.unidata.ucar.edu/browse/NCF-317)
* Added a new file, `netcdf_meta.h`. This file is generated automatically at configure time and contains information related to the capabilities of the netcdf library. This file may be used by projects dependent upon `netcdf` to make decisions during configuration, based on how the `netcdf` library was built. The macro `NC_HAVE_META_H` is defined in `netcdf.h`. Paired with judicious use of `ifdef`'s, this macro will indicate to developers whether or not the meta-header file is present. See [NCF-313](https://bugtracking.unidata.ucar.edu/browse/NCF-313).
* Fixed ncdump bug for char variables with multiple unlimited dimensions and added an associated test. Now the output CDL properly disambiguates dimension groupings, so that ncgen can generate the original file from the CDL. [NCF-310](https://bugtracking.unidata.ucar.edu/browse/NCF-310)
* Converted the [Manually-maintained FAQ page](http://www.unidata.ucar.edu/software/netcdf/docs/faq.html) into markdown and added it to the `docs/` directory. This way the html version will be generated when the rest of the documentation is built, the FAQ will be under version control, and it will be in a more visible location, hopefully making it easier to maintain.
* Bumped minimum required version of `cmake` to `2.8.12`. This was necessitated by the adoption of the new `CMAKE_MACOSX_RPATH` property, for use on OSX.
* Jennifer Adams has requested a reversion in behavior so that all dap requests include a constraint. Problem is caused by change in prefetch where if all variables are requested, then no constraint is generated. Fix is to always generate a constraint in prefetch.
* Added a new option for cmake-based builds, `ENABLE_DOXYGEN_LATEX_OUTPUT`. On those systems with `make` and `pdflatex`, setting this option **ON** will result in pdf versions of the documentation being built. This feature is experimental.
* Bumped minimum CMake version to `2.8.9` from `2.8.8` as part of a larger pull request contributed by Nico Schlömer. [Pull Request #64](https://github.com/Unidata/netcdf-c/pull/64)
* NetCDF creates a `libnetcdf.settings` file after configuration now, similar to those generated by `HDF4` and `HDF5`. It is installed into the same directory as the libraries. [NCF-303](https://bugtracking.unidata.ucar.edu/browse/NCF-303).
* Renamed `man4/` directory to `docs/` to make the purpose and contents clearer. See [man4 vs. docs #60](https://github.com/Unidata/netcdf-c/issues/60).
* Removed redundant variable `BUILD_DOCS` from the CMake configuration file. See the issue at github: [#59](https://github.com/Unidata/netcdf-c/issues/59).
* Added missing documentation templates to `man4/Makefile.am`, to correct an issue when trying to build the local `Doxygen`-generated documentation. This issue was reported by Nico Schlömer and may be viewed on github. [Releases miss Doxygen files #56](https://github.com/Unidata/netcdf-c/issues/56)
* When the NC_MPIPOSIX flag is given for parallel I/O access and the HDF5 library does not have the MPI-POSIX VFD configured in, the NC_MPIPOSIX flag is transparently aliased to the NC_MPIIO flag within the netCDF-4 library.
* As part of an ongoing project, the Doxygen-generated netcdf documentation has been reorganized. The goal is to make the documentation easier to parse, and to eliminate redundant material. This project is ongoing.
* The oc .dodsrc reader was improperly handling the user name and password entries. [NCF-299](https://bugtracking.unidata.ucar.edu/browse/NCF-299)
* CTestConfig.cmake has been made into a template so that users may easily specify the location of an alternative CDash-based Dashboard using the following two options:
*`NC_TEST_DROP_SITE` - Specify an alternative Dashboard by URL or IP address.
*`NC_CTEST_DROP_LOC_PREFIX` - Specify a prefix on the remote webserver relative to the root directory. This lets CTest accommodate dashboards that do not live at the top level of the web server.
* Added a separate flag to enable DAP AUTH tests. These tests are disabled by default. The flags for autotools and CMAKE-based builds are (respectively):
* Corrected "BAIL" macros to avoid infinite loop when logging is disabled and an error occurs.
* Refactored how types are used for attributes, variables, and committed types, clarifying and categorizing fields in structs, and eliminating duplicated type information between variables and types they use.
* Enabled netCDF-4 bit-for-bit reproducibility for nccopy and other applications (thanks to Rimvydas Jasinskas and Quincey Koziol) by turning off HDF5 object creation, access, and modification time tracking. [NCF-290](https://bugtracking.unidata.ucar.edu/browse/NCF-290)
* Addressed an issue where `cmake`-based builds would not properly create a `pkg-config` file. This file is now created properly by `cmake`. [NCF-288](https://bugtracking.unidata.ucar.edu/browse/NCF-288)
* Addressed an issue reported by Jeff Whitaker regarding `nc_inq_nvars` returning an incorrect number of dimensions (this issue was introduced in 4.3.1-rc5). Integrated a test contributed by Jeff Whitaker.
* When compiling with `hdf4` support, both autotools and cmake-based builds now properly look for the `libjpeg` dependency and will link against it when found (or complain if it's not). Also added `ENABLE_HDF4_FILE_TESTS` option to CMake-based builds.
* Added hack to the DAP code to address a problem with the Columbia.edu server. That server does not serve up proper DAP2 DDS replies. The Dataset {...} name changes depending on if the request has certain kinds of constraints. [NCF-276]
* Added a new configuration flag, `NC_USE_STATIC_CRT` for CMake-based Windows builds. The default value is 'OFF'. This will allow the user to define whether to use the shared CRT libraries (\\MD) or static CRT libraries (\\MT) in Visual Studio builds.
* Integrated a fix by Quincey Koziol which addressed a variation of [NCF-250], *Fix issue of netCDF-4 parallel independent access with unlimited dimension hanging*.
* Integrated change contributed by Orion Poplawski which integrated GNUInstallDirs into the netCDF-C CMake system; this will permit systems that install into lib64 (such as Fedora) to `make install` without problem.
* Corrected an error with the CMake config files that resulted in the `netcdf.3` manpage not being built or installed.
* Migrated from the netCDF-C `subversion` repository to a publicly available GitHub repository available at https://github.com/Unidata/netCDF-C. This repository may be checked out (cloned) with the following command:
* Added a `NC_HAVE_RENAME_GRP` macro to netcdf.h, [as per a request by Charlie Zender][cz1]. This will allow software compiling against netcdf to easily query whether or not nc\_rename\_grp() is available.
* Added Greg Sjaardema's contributed optimization for the nc4\_find\_dim\_len function in libsrc4/nc4internal.c. The patch eliminates several malloc/free calls that exist in the original coding.
* Added support for dynamic loading, to compliment the dynamic loading support introduced in hdf 1.8.11. Dynamic loading support depends on libdl, and is enabled as follows: [NCF-258]
* Fix issue of netCDF-4 parallel independent access with unlimited dimension hanging. Extending the size of an unlimited dimension in HDF5 must be a collective operation, so now an error is returned if trying to extend in independent access mode. [NCF-250]
* Fixed bug with netCDF-4's inability to read HDF5 scalar numeric attributes. Also allow, in addition to zero length strings, a new NULL pointer as a string value. to improve interoperability with HDF5. This required a new CDL constant, 'NIL', that can be output from ncdump for such a string value in an HDF5 or netCDF-4 file. The ncgen utility was also modified to properly handle such NIL values for strings. [NCF-56]
* Parallel-build portability fixes, particularly for OpenMPI and gcc/gfortran-4.8.x on OSX.
* Fix contributed by Nath Gopalaswamy to large file problem reading netCDF classic or 64-bit offset files that have a UINT32_MAX flag for large last record size of a variable that has values larger than 1 byte. This problem had previously been fixed for *writing* such data, but was only tested with an ncbyte variable.
