.. auto-generated by script ../../../../utils/nxdl2rst.py from the NXDL source NXaperture.nxdl.xml

.. index::
    ! NXaperture (base class)
    ! aperture (base class)
    see: aperture (base class); NXaperture

.. _NXaperture:

==========
NXaperture
==========

**Status**:

  base class, extends :ref:`NXobject`

**Description**:

  A beamline aperture

**Symbols**:

  No symbol table

**Groups cited**:
  :ref:`NXgeometry`, :ref:`NXnote`, :ref:`NXpositioner`, :ref:`NXtransformations`

.. index:: NXtransformations (base class); used in base class, NXpositioner (base class); used in base class, NXgeometry (base class); used in base class, NXnote (base class); used in base class

**Structure**:

  .. _/NXaperture@default-attribute:

  .. index:: default (file attribute)

  **@default**: (optional) :ref:`NX_CHAR <NX_CHAR>`

    Declares which child group contains a path leading to a :ref:`NXdata` 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.

  .. _/NXaperture/material-field:

  .. index:: material (field)

  **material**: (optional) :ref:`NX_CHAR <NX_CHAR>`

    Absorbing material of the aperture.

  .. _/NXaperture/description-field:

  .. index:: description (field)

  **description**: (optional) :ref:`NX_CHAR <NX_CHAR>`

    Description of the aperture.

  .. _/NXaperture/shape-field:

  .. index:: shape (field)

  **shape**: (optional) :ref:`NX_CHAR <NX_CHAR>`

    Shape of the aperture.

    Any of these values:

      * ``straight slit``

      * ``curved slit``

      * ``pinhole``

      * ``circle``

      * ``square``

      * ``hexagon``

      * ``octagon``

      * ``bladed``

      * ``open``

      * ``grid``


  .. _/NXaperture/size-field:

  .. index:: size (field)

  **size**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    The relevant dimension for the aperture, i.e. slit width, pinhole and iris
    diameter

  .. _/NXaperture/depends_on-field:

  .. index:: depends_on (field)

  **depends_on**: (optional) :ref:`NX_CHAR <NX_CHAR>`

    Specifies the position of the aperture by pointing to the last transformation in
    the transformation chain in the NXtransformations group.

  .. _/NXaperture/TRANSFORMATIONS-group:

  **TRANSFORMATIONS**: (optional) :ref:`NXtransformations`

    Collection of axis-based translations and rotations to describe the location and
    geometry of the deflector as a component in the instrument. Conventions from the
    NXtransformations base class are used. In principle, the McStas coordinate
    system is used. The first transformation has to point either to another
    component of the system or . (for pointing to the reference frame) to relate it
    relative to the experimental setup. Typically, the components of a system should
    all be related relative to each other and only one component should relate to
    the reference coordinate system.

  .. _/NXaperture/POSITIONER-group:

  **POSITIONER**: (optional) :ref:`NXpositioner`

    Stores the raw positions of aperture motors.

  .. _/NXaperture/GEOMETRY-group:

  **GEOMETRY**: (optional) :ref:`NXgeometry`

    Location and shape of the aperture.

  .. _/NXaperture/BLADE_GEOMETRY-group:

  **BLADE_GEOMETRY**: (optional) :ref:`NXgeometry`

    Location and shape of each blade.

  .. _/NXaperture/NOTE-group:

  **NOTE**: (optional) :ref:`NXnote`

    Describes any additional information.


Hypertext Anchors
-----------------

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


* :ref:`/NXaperture/BLADE_GEOMETRY-group </NXaperture/BLADE_GEOMETRY-group>`
* :ref:`/NXaperture/depends_on-field </NXaperture/depends_on-field>`
* :ref:`/NXaperture/description-field </NXaperture/description-field>`
* :ref:`/NXaperture/GEOMETRY-group </NXaperture/GEOMETRY-group>`
* :ref:`/NXaperture/material-field </NXaperture/material-field>`
* :ref:`/NXaperture/NOTE-group </NXaperture/NOTE-group>`
* :ref:`/NXaperture/POSITIONER-group </NXaperture/POSITIONER-group>`
* :ref:`/NXaperture/shape-field </NXaperture/shape-field>`
* :ref:`/NXaperture/size-field </NXaperture/size-field>`
* :ref:`/NXaperture/TRANSFORMATIONS-group </NXaperture/TRANSFORMATIONS-group>`
* :ref:`/NXaperture@default-attribute </NXaperture@default-attribute>`

**NXDL Source**:
  https://github.com/nexusformat/definitions/blob/main/base_classes/NXaperture.nxdl.xml