Data collected by SPEC control and data acquisition software SPEC [#]_ is software for instrument control and data acquisition in X-ray diffraction experiments. .. [#] SPEC: https://certif.com .. index:: plotting Declares which :ref:`NXentry` group contains the data to be shown by default. It is needed to resolve ambiguity when more than one :ref:`NXentry` group exists. The value is the name of the default :ref:`NXentry` group. Version of HDF5 library used in writing the file (as specified in :ref:`NXroot`). Note this attribute is spelled with uppercase "V", different than other version attributes. version of h5py Python package used to write this HDF5 file original SPEC data file name from **#F** line in file header date from **#D** line in file header, in ISO8601 format UNIX time epoch from **#E** line in file header any **#C** lines in file header, stored as one string with newlines between comments Number of header sections found in the spec file one scan from a SPEC data file, starts with a **#S** line .. index:: plotting Declares which :ref:`NXdata` group contains the data to be shown by default. It is needed to resolve ambiguity when more than one :ref:`NXdata` group exists. The value is the name of the default :ref:`NXdata` group. Official NeXus NXDL schema to which this subentry conforms. SPEC scan number SPEC scan number and command, from **#S** line SPEC data file line:: #S 1 cscan en 690 750 60 0 *title*:: 1 cscan en 690 750 60 0 SPEC scan command, from **#S** line, after the scan number. :SPEC data file line: ``#S 1 cscan en 690 750 60 0`` :command*: ``cscan en 690 750 60 0`` date from **#D** line in scan header, in ISO8601 format Count to a preset value based on either clock time (timer) or received monitor counts (monitor). preset value for time or monitor * **#M** -- counting against this constant monitor count (see #T) * **#T** -- counting against this constant number of seconds (see #M) array(s) of monitor data array(s) of monitor data Any **#C** lines in this scan, stored as one string with newlines between comments **#Q** -- :math:`Q` (:math:`hkl`) at start of scan array of [:math:`h` :math:`k` :math:`l`] **#X** -- temperature set point **#X** -- temperature set point (C) detector (and MCA) data from this scan name of the field with the plottable data, typically the last column for 1-D scans This is the primary dependent axis, such as two-theta detector. This field must exist (or be linked) in this :ref:`NXdata` group. name(s) of the field(s) for plotting the data, typically the first column for 1-D scans These are the independent axes, such as positioners. For 2-D or higher dimension data, there will be a field named for each dimension, separated by ":" (preferred) or "," or " " (whitespace). Such as for 2-D data plotted against *energy* and *th*:: @axes = energy:th This(these) field(s) must exist (or be linked) in this :ref:`NXdata` group. For each field named in *@axes*, there will be an instance of this attribute, defining into which dimensions of the *@signal* data this field applies. The value of this attribute is a list of index numbers using 0-based indexing (first dimension is 0, seconds i 1, ...). Such as for 2-D data plotted against *energy* and *th*:: @energy_indices = [0] @th_indices = [1] one column of data from the scan HDF5 requires that each member of a group must have a unique name. Pick the name of column from **#L** but make it unique which means if the same name is used in more than one column, append a number to the extra instances to make them unique yet preserve their content, just in case they might be different. Example: ``seconds seconds`` becomes ``seconds`` and ``seconda_1``. name as specified in **#L** line, before it was made unique for HDF5 Unless stated otherwise, units (not declared in the SPEC data file) are assumed to be *counts* for detectors and "unknown" for positioners or other scan columns. **#I** -- intensity normalizing factor associates values declared in **#J** and **#j** scan header lines associates values declared in **#O** and **#o** scan header lines various metadata from the SPEC scan header that have well-known NeXus base clases Orientation matrix of single crystal sample using Busing-Levy convention **#G3** line in scan header SPEC geometry variables for this diffractometer geometry (instrument specific) TODO: give interpreted name for each array value (need to figure out how to get the names) geometry parameters from G[] array (geo mode, sector, etc) geometry parameters from U[] array (lattice constants, orientation reflections) not used, although some files has a single zero value geometry parameters from Q[] array (lambda, frozen angles, cut points, etc) names and values of all positioners (**#O** and **#P** lines) in scan header one positioner from the scan header HDF5 requires that each member of a group must have a unique name. SPEC assigns a unique name to each positioner, no extra work is neccesary to comply with the HDF5 rule for unique names in a group. **#@CALIB** -- coefficients to compute a scale based on the MCA channel number numbered regions of interest, use an index number as part of the name ``first_channel, last_channel`` SPEC metadata (UNICAT-style #H and #V lines) This is a block that may be unique to SPEC files acquired at certain APS beam lines. Other facilities or instruments may use this block for storing key:value pairs of data where the values have suitable attributes (such as units). user name from first **#C** line in file header Fallback for any SPEC data file control lines not otherwise placed into groups or fields elsewhere in this specification.