[2020.02] - 2020-05-01 Added FMS2_IO: An fms2_io_nml namelist has been created. It includes the variable ncchksz. This is the replacement for the environment variable NC_BLKSZ set in model run scripts and used by mpp_io. The default value is 64 KB. Any time a file is opened in fms2_io (nf90_open or nf90_create), the optional argument chunksize=ncchksz is passed to the NetCDF library. NetCDF attempts to use this value to control the blocksize utilized for reads and writes of data from the filesystem. FMS2_IO: Adds support to compute_global_cheksum.inc for real32, assuming the flag -DOVERLOAD_R4 is used when compiling. Changed MPP_DOMAINS - nesting: The logic supporting nested domains for mosaic grids has been overhauled and extended. FMS now supports multiple nests and telescoping nests (nest embedded within a nest). The requirement for a nest to lie wholly within a single tile has been relaxed and a first-level nest may cross tile boundaries, but may not contain a tile corner. Communications for two-way nesting have also been improved. The 2019 December Public Release and 2020.02 GFDL Release within the [GFDL_atmos_cubed_sphere] (https://github.com/NOAA-GFDL/GFDL_atmos_cubed_sphere) have been updated and are compatible with this release of FMS. FMS2_IO: The intent of fileobj is changed from (in) to (inout) in netcdf_restore_state_wrap, restore_domain_state, and netcdf_restore_state because the file object type has a pointer that is being reassigned in one of the routines lower in the call stack. Deprecated MPP_DOMAINS - nesting: The initial nesting implementation is no longer supported. Please see the Changed::MPP_DOMAINS sub-entry under. Removed GENERAL: References to the macro _ALLOCATABLE have been replaced with "allocatable", _ALLOCATED has been replaced with "allocated", and _NULL has been removed. It is now assumed that all compilers support the Fortran 2003 standard. The macros still exist in fms_platforms.h for compatibility within other components. DIAG_MANAGER: "fms_platform.h" is no longer included in any of the diag_manager routines. Instead, fms_platform_mod is now being use-associated where necessary. This fixes an issue for debuggers not providing correct line numbers. Known Issues DIAG_MANAGER: The regional diagnostics are not reproducing old behavior of a mat table it used to write the output. Regional diagnostics without a mask table should reproduce.