When both the HDF5 library and the application are built and installed with no specific compatibility flags, H5A_ITERATE is mapped to the most recent version of the function, currently H5A_ITERATE2. If the library and/or application is compiled for Release 1.6 emulation, H5A_ITERATE will be mapped to H5A_ITERATE1. Function-specific flags are available to override these settings on a function-by-function basis when the application is compiled.
Specific compile-time compatibility flags and the resulting mappings are as follows:
Interface history: Signature  above is the original H5Aiterate interface and the only interface available prior to HDF5 Release 1.8.0. This signature and the corresponding function are now deprecated but will remain directly callable as H5A_ITERATE1.
Signature  above was introduced with HDF5 Release 1.8.0 and is the recommended and default interface. It is directly callable as H5A_ITERATE2.
See API Compatibility Macros in HDF5 for circumstances under which either of these functions might not be available in an installed instance of the HDF5 library.
The function H5Aiterate renamed to H5Aiterate1 and deprecated in this release. The macro H5Aiterate and the functions H5Aiterate2 and H5Aiterate_by_name introduced in this release.