Glossary

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A B C D E F G H I L M N O P R S U V

See the current version.

A

Array datatype 
A family of HDF5 datatypes whose elements are arrays of a fixed rank (≤ 32) and fixed finite extent. All array elements must be of the same HDF5 datatype.

B

Bitfield datatype 
A family of HDF5 datatypes whose elements are fixed-width bit fields.

C

Chunked layout 
A dataset storage layout where the dataset elements are partitioned into fixed-size multi-dimensional chunks or tiles. Chunked layout is mandatory for datasets with one or more dimensions of indefinite (infinite) extent or where compression or other filters are applied to the dataset elements.
Chunked layout may improve I/O performance for certain access patterns.

D

Dataset 
A kind of HDF5 object, a linked array variable. which can be located in an HDF5 file through a path name. Datasets are commonly used to store "heavy-weight" problem-sized data.
The HDF5 library offers a lot of features aimed at optimized dataset access and storage, including compression and partial I/O.

E

Enumeration datatype 
A family of HDF5 datatypes whose elements represent named integer values called members or enumerators. Currently, only ASCII names are supported.

F

Field 
See compound datatype.

G

Group 
A kind of HDF5 object that stores a collection of HDF5 links. Each HDF5 file contains at least one group, it's root group.
Among the destinations of an HDF5 group's links may be other HDF5 groups (including the group itself!). This ability is sometimes referred to as the closure property of groups. It is the basis for creating hierarchical or more general graph-like structures.

H

Hard link 
An HDF5 link whose destination is specified (internally) as the address of an HDF5 object in the same HDF5 file.

I

Identifier 
An opaque, transient handle used by the HDF5 library to manipulate in-memory representations of HDF5 items.

J

K

L

Library 
Link 
A named, uni-directional association between a source and a destination. In HDF5, the source is always the HDF5 group that hosts the link in its link collection.
There are several ways to specify a link's destination:
  • The address of an HDF5 object in the same HDF5 file; so-called hard link.
  • A path name in the same or a different file; so-called soft or external link.
  • User-defined
A link name can be any Unicode string that does not contain slashes ("/") or consists of a single dot character ("."). A link name must be unique in a group's link collection.

M

Metadata 
Data that in a given context has a descriptive or documentation function for other data. Typically, the metadata is small compared to the data it describes.

N

Name 
A Unicode string that depending on the item it names might be subject to certain character restrictions. In HDF5, the user might encounter the following names:
  1. A link name
  2. A path name
  3. An attribute name
  4. A field name
  5. A tag name
  6. A file name

O

Object 
An HDF5 group, dataset or named datatype; an HDF5 item that can be linked to zero or more groups and decorated with zero or more HDF5 attributes.

P

Path name 
A Unicode string that is the concatenation of link names separated by slashes ('/'). In HDF5, path names are used to locate and refer to HDF5 objects.

Q

R

Rank 
The number of dimensions of a non-null dataspace.

S

Scalar dataspace 
A kind of HDF5 dataspace that has the shape of a singleton, i.e., a set containing a single element. Array variables with this shape store exactly one element.

T

U

User block 
An HDF5 file format primitive that allows one to set aside a fixed-size (at least 512 bytes or any power of 2 thereafter) contiguous range of bytes at the beginning of an HDF5 file for application purposes which will be skipped/ignored by the HDF5 library.

V

Variable-length datatype 
A family of HDF5 datatypes whose elements are variable-length sequences of a given datatype.

W

X

Y

Z