HDF5 Predefined Datatypes

The following datatypes are predefined in HDF5.

IEEE floating point datatypes

32-bit and 64-bit
Big-endian and little-endian

        H5T_IEEE_F32BE
        H5T_IEEE_F32LE
        H5T_IEEE_F64BE
        H5T_IEEE_F64LE

Standard datatypes

Signed integer (2's complement), unsigned integer, and bitfield
8-bit, 16-bit, 32-bit, and 64-bit
Big-endian and little-endian

        H5T_STD_I8BE
        H5T_STD_I8LE
        H5T_STD_I16BE
        H5T_STD_I16LE
        H5T_STD_I32BE
        H5T_STD_I32LE
        H5T_STD_I64BE
        H5T_STD_I64LE

        H5T_STD_U8BE 
        H5T_STD_U8LE
        H5T_STD_U16BE
        H5T_STD_U16LE
        H5T_STD_U32BE
        H5T_STD_U32LE
        H5T_STD_U64BE 
        H5T_STD_U64LE

        H5T_STD_B8BE
        H5T_STD_B8LE
        H5T_STD_B16BE 
        H5T_STD_B16LE
        H5T_STD_B32BE
        H5T_STD_B32LE
        H5T_STD_B64BE 
        H5T_STD_B64LE

Object reference or dataset region reference

        H5T_STD_REF_OBJ
        H5T_STD_REF_DSETREG

UNIX-specific datatypes

32-bit and 64-bit
Big-endian and little-endian

        H5T_UNIX_D32BE
        H5T_UNIX_D32LE
        H5T_UNIX_D64BE
        H5T_UNIX_D64LE

C-specific datatype

String datatype in C (size defined in bytes rather than in bits)

        H5T_C_S1

FORTRAN-specific datatype

String datatype in FORTRAN (as defined for the HDF5 C library)

        H5T_FORTRAN_S1

Intel-specific datatypes

For Intel CPUs
Little-endian
Signed integer (2's complement), unsigned integer, bitfield, and IEEE floating point
8-bit, 16-bit, 32-bit, and 64-bit

        H5T_INTEL_I8
        H5T_INTEL_I16
        H5T_INTEL_I32
        H5T_INTEL_I64

        H5T_INTEL_U8
        H5T_INTEL_U16
        H5T_INTEL_U32
        H5T_INTEL_U64

        H5T_INTEL_B8
        H5T_INTEL_B16
        H5T_INTEL_B32
        H5T_INTEL_B64

        H5T_INTEL_F32
        H5T_INTEL_F64

DEC Alpha-specific datatypes

For DEC Alpha CPUs
Little-endian
Signed integer (2's complement), unsigned integer, bitfield, and IEEE floating point
8-bit, 16-bit, 32-bit, and 64-bit

        H5T_ALPHA_I8
        H5T_ALPHA_I16
        H5T_ALPHA_I32
        H5T_ALPHA_I64

        H5T_ALPHA_U8
        H5T_ALPHA_U16
        H5T_ALPHA_U32
        H5T_ALPHA_U64

        H5T_ALPHA_B8
        H5T_ALPHA_B16
        H5T_ALPHA_B32
        H5T_ALPHA_B64

        H5T_ALPHA_F32
        H5T_ALPHA_F64

OpenVMS DEC Alpha-specific datatypes

For OpenVMS on DEC Alpha CPUs
VAX byte order
32- and 64-bit floating point

        H5T_VAX_F32 (Corresponds to F_Floating type)
        H5T_VAX_F64 (Corresponds to G_Floating type)

MIPS-specific datatypes

For MIPS CPUs, commonly used in SGI system
Big-endian
Signed integer (2's complement), unsigned integer, bitfield, and IEEE floating point
8-bit, 16-bit, 32-bit, and 64-bit

        H5T_MIPS_I8
        H5T_MIPS_I16
        H5T_MIPS_I32
        H5T_MIPS_I64

        H5T_MIPS_U8
        H5T_MIPS_U16
        H5T_MIPS_U32
        H5T_MIPS_U64

        H5T_MIPS_B8
        H5T_MIPS_B16
        H5T_MIPS_B32
        H5T_MIPS_B64

        H5T_MIPS_F32
        H5T_MIPS_F64

Predefined native datatypes

These are the datatypes detected by H5detect. Their names differ from other HDF5 datatype names as follows:

Instead of a class name, precision, and byte order as the last component, they have a C-like datatype name.
If the datatype begins with U, then it is the unsigned version of the integer datatype; other integer datatypes are signed.
The datatype LLONG corresponds to C's long_long and LDOUBLE is long_double. These datatypes might be the same as LONG and DOUBLE, respectively.

        H5T_NATIVE_CHAR
        H5T_NATIVE_SCHAR        
        H5T_NATIVE_UCHAR        

        H5T_NATIVE_SHORT        
        H5T_NATIVE_USHORT       

        H5T_NATIVE_INT          
        H5T_NATIVE_UINT         

        H5T_NATIVE_LONG         
        H5T_NATIVE_ULONG        
        H5T_NATIVE_LLONG        
        H5T_NATIVE_ULLONG

        H5T_NATIVE_FLOAT        
        H5T_NATIVE_DOUBLE       
        H5T_NATIVE_LDOUBLE

        H5T_NATIVE_B8
        H5T_NATIVE_B16
        H5T_NATIVE_B32
        H5T_NATIVE_B64

        H5T_NATIVE_OPAQUE       
        H5T_NATIVE_HADDR
        H5T_NATIVE_HSIZE
        H5T_NATIVE_HSSIZE
        H5T_NATIVE_HERR
        H5T_NATIVE_HBOOL

ANSI C9x-specific native integer datatypes

Signed integer (2's complement), unsigned integer, and bitfield
8-bit, 16-bit, 32-bit, and 64-bit
LEAST -- storage to use least amount of space
FAST -- storage to maximize performance

        H5T_NATIVE_INT8
        H5T_NATIVE_UINT8
        H5T_NATIVE_INT_LEAST8
        H5T_NATIVE_UINT_LEAST8
        H5T_NATIVE_INT_FAST8 
        H5T_NATIVE_UINT_FAST8

        H5T_NATIVE_INT16
        H5T_NATIVE_UINT16
        H5T_NATIVE_INT_LEAST16
        H5T_NATIVE_UINT_LEAST16
        H5T_NATIVE_INT_FAST16
        H5T_NATIVE_UINT_FAST16

        H5T_NATIVE_INT32
        H5T_NATIVE_UINT32
        H5T_NATIVE_INT_LEAST32
        H5T_NATIVE_UINT_LEAST32
        H5T_NATIVE_INT_FAST32
        H5T_NATIVE_UINT_FAST32

        H5T_NATIVE_INT64
        H5T_NATIVE_UINT64
        H5T_NATIVE_INT_LEAST64
        H5T_NATIVE_UINT_LEAST64 
        H5T_NATIVE_INT_FAST64
        H5T_NATIVE_UINT_FAST64

FORTRAN90 API datatypes

Datatypes defined for the FORTRAN90 APIs
Native integer, single-precision real, double-precision real, and character

        H5T_NATIVE_INTEGER
        H5T_NATIVE_REAL
        H5T_NATIVE_DOUBLE
        H5T_NATIVE_CHARACTER

Signed integer (2's complement), unsigned integer, and IEEE floating point
8-bit, 16-bit, 32-bit, and 64-bit
Big-endian and little-endian

        H5T_STD_I8BE
        H5T_STD_I8LE
        H5T_STD_I16BE
        H5T_STD_I16LE
        H5T_STD_I32BE
        H5T_STD_I32LE
        H5T_STD_I64BE
        H5T_STD_I64LE

        H5T_STD_U8BE
        H5T_STD_U8LE
        H5T_STD_U16BE
        H5T_STD_U16LE
        H5T_STD_U32BE
        H5T_STD_U32LE
        H5T_STD_U64BE
        H5T_STD_U64LE

        H5T_IEEE_F32BE
        H5T_IEEE_F32LE
        H5T_IEEE_F64BE
        H5T_IEEE_F64LE

Object reference or dataset region reference

        H5T_STD_REF_OBJ
        H5T_STD_REF_DSETREG

HDF5 documents and links
Introduction to HDF5
HDF5 User Guide

The HDF Group Help Desk:

Describes HDF5 Release 1.8.7, targeted for May 2011.