These symbols will be used below to coordinate datasets with the same shape. rank of the data field length of the variable field length of the x field length of the y field length of the z field (required) NXdata is a template of plottable data and their dimension scales. NeXus basic motivation default plot It is mandatory that there is at least one NXdata group in each NXentry group. Note that the variable and data can be defined with different names. The signal and axes attribute of the data item define which items are plottable data and which are dimension scales. NeXus basic motivation default plot Each NXdata group will consist of only one data set containing plottable data and their standard deviations. This data set may be of arbitrary rank up to a maximum of NX_MAXRANK=32. The plottable data will be identified by the attribute: signal="1" The plottable data will identify the dimension scale(s) in the axes attribute. If available, the standard deviations of the data are to be stored in a data set of the same rank and dimensions, with the name errors. For each data dimension, there should be a one-dimensional array of the same length. These one-dimensional arrays are the dimension scales of the data, i.e. the values of the independent variables at which the data is measured, such as scattering angle or energy transfer. There are two methods of linking link each data dimension to its respective dimension scale. The preferred (and recommended) method uses the axes axes attribute to specify the names of each dimension scale. The older method uses the axis attribute on each dimension scale to identify with an integer the axis whose value is the number of the dimension. NXdata is used to implement one of the basic motivations in NeXus, to provide a default plot for the data of this NXentry. The actual data might be stored in another group and (hard) linked to the NXdata group. Dimension scale defining an axis of the data. Client is responsible for defining the dimensions of the data. The name of this field may be changed to fit the circumstances. Standard NeXus client tools will use the attributes to determine how to use this field. A dimension scale must have a rank of 1 and has length n. Axis label 0|false: single value, 1|true: multiple values Index of first good value Index of last good value Index (positive integer) identifying this specific set of numbers. N.B. The axis attribute is the old way of designating a link. Do not use the axes attribute with the axis attribute. The axes attribute is now preferred. Errors (uncertainties) associated with axis variable Client is responsible for defining the dimensions of the data. The name of this field may be changed to fit the circumstances but is matched with the variable field with _errors appended. A dimension scale must have a rank of 1 and has length n, same as variable. This field contains the data values to be used as the NeXus plottable data. NeXus basic motivation default plot Client is responsible for defining the dimensions of the data. The name of this field may be changed to fit the circumstances. Standard NeXus client tools will use the attributes to determine how to use this field. The rank (dataRank) of the data must satisfy 1 <= dataRank <= NX_MAXRANK=32. At least one dim must have length n. Plottable (independent) axis, indicate index number. NeXus basic motivation default plot Only one field in a NXdata group may have the signal="1" attribute. Do not use the signal attribute with the axis attribute. Defines the names of the dimension scales (independent axes) for this data set as a colon-delimited array. N.B. The axes attribute is the preferred method of designating a link. Do not use the axes attribute with the axis attribute. Specify the names of the errors (uncertainties) of the dependent axes as plottable data. N.B. The errors attribute uses the same syntax as the axes attribute. data label Standard deviations of data values - the data array is identified by the attribute signal="1". The errors array must have the same dimensions as data. Client is responsible for defining the dimensions of the data. The errors must have the same rank (dataRank) as the data. At least one dim must have length "n". The elements in data are usually float values really. For efficiency reasons these are usually stored as integers after scaling with a scale factor. This value is the scale factor. It is required to get the actual physical value, when necessary. An optional offset to apply to the values in data. This is an array holding the values to use for the x-axis of data. The units must be appropriate for the measurement. This is an array holding the values to use for the y-axis of data. The units must be appropriate for the measurement. This is an array holding the values to use for the z-axis of data. The units must be appropriate for the measurement.