2.3.3.1.58. NXroot

Status:

base class, extends none

Description:

The root of a NeXus file. ...

The root of a NeXus file.

In the NeXus standard, only NXentry groups are allowed at the root level of a file, although it is permitted to include additional groups and fields that are not part of the NeXus standard and will not be validated by NeXus tools. NeXus defines a number of root-level attributes that can be used to annotate the NeXus tree.

Note that NXroot is the only base class that does not inherit from the NXobject class, since the latter permits the inclusion of NeXus objects that are not allowed at the root level.

Symbols:

No symbol table

Groups cited:

NXentry

Structure:

@file_time: (optional) NX_DATE_TIME

Date and time file was originally created

@file_name: (optional) NX_CHAR

File name of original NeXus file

@file_update_time: (optional) NX_DATE_TIME

Date and time of last file change at close

@NeXus_version: (optional) NX_CHAR

Version of NeXus API used in writing the file. ...

Version of NeXus API used in writing the file.

Note that this is different from the version of the base class or application definition version number.

@NeXus_repository: (optional) NX_CHAR

A repository containing the application definitions ...

A repository containing the application definitions used for creating this file. If the NeXus_release attribute contains a commit distance and hash, this should refer to this repository.

@NeXus_release: (optional) NX_CHAR

The version of NeXus definitions used in writing the file. This can either be ...

The version of NeXus definitions used in writing the file. This can either be a date-based NeXus release (e.g., YYYY.MM), see https://github.com/nexusformat/definitions/releases or a version tag that includes additional development information, such as a commit distance and a Git hash. This is typically formatted as vYYYY.MM.post1.dev<commit-distance>-g<git-hash>, where YYYY.MM refers to the base version of the NeXus definitions. post1.dev<commit-distance> indicates that the definitions are based on a commit after the base version (post1), with <commit-distance> being the number of commits since that version. g<git-hash> is the abbreviated Git hash that identifies the specific commit of the definitions being used.

If the version includes both a commit distance and a Git hash, the NeXus_repository attribute must be included, specifying the URL of the repository containing that version.

@HDF_version: (optional) NX_CHAR

Version of HDF (version 4) library used in writing the file

@HDF5_Version: (optional) NX_CHAR

Version of HDF5 library used in writing the file. ...

Version of HDF5 library used in writing the file.

Note this attribute is spelled with uppercase “V”, different than other version attributes.

@XML_version: (optional) NX_CHAR

Version of XML support library used in writing the XML file

@h5py_version: (optional) NX_CHAR

Version of h5py Python package used in writing the file

@partial: (optional) NX_CHAR

A list of concepts in an application definition this file describes. ...

A list of concepts in an application definition this file describes. This is for partially filling an application definition. If this attribute is not present the application definition is assumed to be valid, if not only the specified concepts/paths are assumed to be valid.

@creator: (optional) NX_CHAR

facility or program where file originated

@creator_version: (optional) NX_CHAR

Version of facility or program used in writing the file

@default: (optional) NX_CHAR

Declares which :ref:`NXentry` group contains ...

Declares which NXentry group contains the data to be shown by default. It is used to resolve ambiguity when more than one NXentry group exists. The value names the default NXentry group. The value must be the name of a child of the current group. The child must be a NeXus group or a link to a NeXus group.

It is recommended (as of NIAC2014) to use this attribute to help define the path to the default dataset to be plotted. See https://www.nexusformat.org/2014_How_to_find_default_data.html for a summary of the discussion.

ENTRY: (optional) NXentry

entries

Hypertext Anchors

List of hypertext anchors for all groups, fields, attributes, and links defined in this class.

NXDL Source:

https://github.com/FAIRmat-NFDI/nexus_definitions/tree/fairmat/base_classes/NXroot.nxdl.xml