diff --git a/doc/dev/hiresconfig.rst b/doc/dev/hiresconfig.rst
new file mode 100644
index 0000000000..df3b4db701
--- /dev/null
+++ b/doc/dev/hiresconfig.rst
@@ -0,0 +1,115 @@
+.. include:: ../include/links.rst
+
+.. _hires_config:
+
+Automated sorting of HIRES frames by instrument configuration
+=============================================================
+
+Version History
+---------------
+
+
+=========   ================   =========== ===========
+*Version*   *Author*           *Date*      ``PypeIt``
+=========   ================   =========== ===========
+1.0         Debora Pelliccia   17 Jun 2024 1.15.1.dev
+=========   ================   =========== ===========
+
+----
+
+Basics
+------
+
+To prepare for the data reduction, PypeIt, first, automatically associates fits
+files to specific :ref:`frame_types` (see :ref:`hires_frames`) and, then,
+collects groups of frames in unique instrument configurations (see below). This is performed
+by the :ref:`pypeit_setup` script, which sorts the frames and writes a
+:ref:`pypeit_file` for each unique configuration. See :ref:`setup_doc`.
+
+
+HIRES configuration identification
+---------------------------------
+
+The HIRES instrument configurations are determined by the function
+:func:`pypeit.metadata.PypeItMetaData.unique_configurations`,
+which finds unique combinations of the following keywords:
+
+===============     ============
+``fitstbl`` key     Header Key
+===============     ============
+``dispname``        ``XDISPERS``
+``decker``          ``DECKNAME``
+``binning``         ``BINNING``
+``filter1``         ``FIL1NAME``
+``echangle``        ``ECHANGL``
+``xdangle``         ``XDANGL``
+===============     ============
+
+The unique configurations are determined by collating the relevant metadata from the headers
+of all frames found by a run of :ref:`pypeit_setup`, *except* those that are designated as
+bias and slitless_pixflat frames. Bias and slitless_pixflat frames can have header data (e.g., ``filter1``)
+that do not match the instrument configuration that an observer intended for their use.
+Therefore, PypeIt uses the ``dispname`` and ``binning`` keys to match the bias and
+slitless_pixflat frames to the configurations with frames taken with the same cross-disperser
+and same binning.
+
+After that, :func:`pypeit.metadata.PypeItMetaData.set_configurations` associates each frame
+to the relevant unique configuration ("setup"), by assigning a setup identifier
+(e.g., A,B,C,D...) to every frames for which the values of the above keywords match the
+values of the specific unique configuration.
+
+HIRES calibration groups
+-----------------------
+
+PypeIt uses the concept of a "calibration group" to define a complete set of
+calibration frames (e.g., arcs, flats) and the science frames to which these calibration
+frames should be applied.
+
+By default, :ref:`pypeit_setup` uses the setup identifier to assign frames to a single
+calibration group. Frames that are in the same calibration group will have the same PypeIt
+keyword ``calib``. No automated procedure exists to do anything except this.
+However, the user can edit the :ref:`pypeit_file` to, within a given configuration, assign
+specific calibration frames to specific science frames using the data in the ``calib`` column
+of the :ref:`data_block`.
+
+Testing
+-------
+
+To test that PypeIt can successfully identify multiple
+configurations among a set of files, we have added the
+``test_setup_keck_hires_multiconfig()`` test to
+``${PYPEIT_DEV}/unit_tests/test_setups.py``.
+
+Here is an example of how to run the test:
+
+.. code-block:: bash
+
+    cd ${PYPEIT_DEV}/unit_tests
+    pytest test_setup.py::test_setup_keck_hires_multiconfig -W ignore
+
+The tests require that you have downloaded the PypeIt
+:ref:`dev-suite` and defined the ``PYPEIT_DEV`` environmental
+variable that points to the relevant directory.
+
+The algorithm for this test is as follows:
+
+    1. Collect the names of all files in selected HIRES directories.
+
+    2. Use :class:`~pypeit.pypeitsetup.PypeItSetup` to automatically
+       identify the configurations for these files.
+
+    3. Check that the code found two configurations and wrote the
+       pypeit files for each.
+
+    4. For each configuration:
+
+        a. Read the pypeit file
+
+        b. Check that the name for the setup is correct ('A' or 'B')
+
+        c. Check that the calibration group is the same for all frames ('0' or '1')
+
+
+Because these tests are now included in the PypeIt
+:ref:`unit-tests`, these configuration checks are performed by the
+developers for every new version of the code.
diff --git a/doc/dev/hiresframes.rst b/doc/dev/hiresframes.rst
index dacfd52861..557d852bdd 100644
--- a/doc/dev/hiresframes.rst
+++ b/doc/dev/hiresframes.rst
@@ -33,15 +33,15 @@ set of criteria used to classify the frame type.
 The header cards required for the frame-typing and their associated keyword in the
 :class:`~pypeit.metadata.PypeItMetaData` object are:
 
-===============     ======================================================
+===============     ============
 ``fitstbl`` key     Header Key
-===============     ======================================================
+===============     ============
 ``exptime``         ``ELAPTIME``
 ``hatch``           ``HATOPEN``
 ``lampstat01``      See below
 No key              ``XCOVOPEN``
 No key              ``AUTOSHUT``
-===============     ======================================================
+===============     ============
 
 ``lampstat01`` is defined using a combination of header keywords, which include
 ``LAMPCAT1``, ``LAMPCAT2``, ``LAMPQTZ2``, ``LAMPNAME``. If ``LAMPCAT1 = True`` or