diff --git a/docs/source/api/python/techniques/ISISPowder-GEM-v1.rst b/docs/source/api/python/techniques/ISISPowder-GEM-v1.rst
new file mode 100644
index 0000000000000000000000000000000000000000..fbda99d11928c27b9583c7490e01e54c4ab66ae7
--- /dev/null
+++ b/docs/source/api/python/techniques/ISISPowder-GEM-v1.rst
@@ -0,0 +1,222 @@
+.. _isis-powder-diffraction-gem-ref:
+
+=======================================
+ISIS Powder Diffraction Scripts - Gem
+=======================================
+
+.. warning:: These scripts and documentation are still undergoing active development.
+             They can change in any way during these stages and the validity of all
+             data has not been tested.
+
+.. contents:: Table of Contents
+    :local:
+
+
+
+.. _gem_calibration_folder-powder-diffraction-ref:
+
+Calibration Folder
+------------------
+Within the top level of the calibration folder for gem the following
+must be present:
+
+- Folder for each cycle label (e.g. 10_2) containing a .cal file with detector
+  offsets and grouping information for that cycle
+
+The names of the .cal grouping file and masking file are set in the advanced
+configuration file. See: :ref:`gem_advanced_config-powder-diffraction-ref`
+
+The label for the run being processed and the appropriate offset filename is
+read from the calibration mapping file: :ref:`gem_calibration_map-powder-diffraction-ref`
+
+.. _gem_calibration_map-powder-diffraction-ref:
+
+Calibration Configuration File
+------------------------------
+An example of the file layout is below:
+
+.. code-block:: yaml
+  :linenos:
+
+  123-130, 135-140:
+    label : "10_1"
+    offset_file_name : "offsets_example_10_1.cal"
+    vanadium_run_numbers : "123-125"
+    empty_run_numbers : "126-130"
+
+  141-145:
+    label : "10_2"
+    ...etc.
+
+Line 1 is documented here: :ref:`calibration_map_isis-powder-diffraction-ref`
+
+The subsequent lines can be placed in any order provided that blocks (which are
+marked by the indentation of the line) remain together. This is further explained
+below.
+
+- Line 2 sets the label that is associated with any runs specified in line 1
+  and is used for the calibration and output directories
+- Line 3 sets the name of the offset and grouping file to use.
+  See TODO link (calibration folder)
+- Line 4 the vanadium run numbers associated with this label
+- Line 5 is the empty run numbers for this label
+- Line 6 - Is an empty line - this is ignored
+- Line 7 Is the start of the next block of runs (see line 1). ...etc.
+
+Basic Script Parameters
+-----------------------
+For background on script parameters and how they are evaluated see:
+:ref:`script_param_overview_isis-powder-diffraction-ref`
+
+- `calibration_directory` - The location of the calibration folder. The structure
+  of the folder is described here: :ref:`gem_calibration_folder-powder-diffraction-ref`
+  Additionally calibrated vanadium data will be stored here for later
+  use whilst focusing.
+
+- `calibration_mapping_file` - The full path to the YAML mapping of run numbers,
+  label and vanadium/empty runs. This is described in more detail here:
+  :ref:`gem_calibration_map-powder-diffraction-ref`
+
+- `config_file` - The full path to the YAML configuration file. The full description
+  of this file is here: :ref:`calibration_map_isis-powder-diffraction-ref`
+
+- `do_absorb_corrections` - Used during a vanadium calibration and subsequent focusing
+  if set to True the calibration routine will correct for absorption and scattering
+  in a cylindrical sample as defined in the advanced configuration file. It then applies
+  these calibrations to the vanadium sample.
+
+- `input_mode` - Specifies how the runs are processed. Accepted values `Individual`,
+  `Summed` - TODO write section on input modes for overview
+
+- `multiple_scattering` - If set to True with `do_absorb_corrections` the calculation
+  will factor in the effects of multiple scattering and apply the correct corrections.
+
+- `run_in_range` - Only used during vanadium calibration. The run specified here
+  is used with to determine the current label and the correct runs to use whilst
+  calculating the calibration. See :ref:`gem_calibration_map-powder-diffraction-ref`
+
+- `run_number` - used during focusing, a single run or range of runs can be specified here.
+  All ranges specified are processed inclusively with the behavior determined by
+  `input_mode`. See TODO link
+
+- `output_directory` - The folder where the data is saved. The data is saved
+  in a folder with the label appropriate for that/those run(s) and the user name
+  specified by the user.
+
+- `user_name` - Specifies the user name to use when saving out focused data.
+
+- `vanadium_normalisation` - If set to True divides the sample by the calculated vanadium
+  spline during the normalisation step.
+
+.. _gem_advanced_config-powder-diffraction-ref:
+
+Advanced Script Parameters
+--------------------------
+
+- `grouping_file_name` - The name of the .cal file containing grouping information
+  for the detectors. This file must be located at the top of the calibration
+  directory as noted here :ref:`gem_calibration_folder-powder-diffraction-ref`
+
+- `masking_file_name` - The name of the file containing Vanadium masking information.
+  This file must be located at the top of the calibration directory as noted here:
+  :ref:`gem_calibration_folder-powder-diffraction-ref`
+
+- `focused_cropping_values` - Stores the TOF window to crop down to on a bank-by-bank
+   basis. This is one of the final steps applied to a focused workspace. The values
+   are stored as a list of tuples, with one tuple per bank and each containing
+   the minimum and maximum values in TOF. The window specified must be less than
+   both `vanadium_cropping_values` and `raw_data_tof_cropping`
+
+- `raw_data_cropping_values` - The window in TOF which the data should be cropped
+  down to before any processing. This should be stored as a tuple of minimum and
+  maximum TOF values. The window should be larger than `vanadium_cropping_values`.
+
+- `spline_coefficient` - The coefficient to use whilst taking a b-spline of the
+  Vanadium workspace during calibration
+
+- `vanadium_cropping_values` - Stores the TOF window the vanadium workspace is
+  cropped down to after focusing. This value is stored as a tuple of the minimum
+  and maximum values. The TOF window should be smaller than `raw_data_cropping_values`
+  but larger than `tof_cropping_ranges`
+
+Configuring the Scripts
+-----------------------
+The scripts are objected oriented - for more information on this concept see
+:ref:`script_param_overview_isis-powder-diffraction-ref`
+
+The following parameters must be included in the object construction step.
+They can either be manually specified or set in the configuration file:
+
+- calibration_directory
+- output_directory
+- user_name
+
+The first step is importing the correct scripts for the gem instrument:
+
+
+.. code-block:: python
+
+  # First import the scripts for Gem
+  from isis_powder.gem import Gem
+
+The scripts can be setup in 3 ways:
+
+1. Explicitly setting all parameters:
+
+.. code-block:: python
+
+  gem_manually_specified = Gem(user_name="Mantid",
+                               calibration_directory="<Path to Calibration folder>",
+                               output_directory="<Path to output folder>")
+
+2. Using user configuration files see :ref:`yaml_basic_conf_isis-powder-diffraction-ref`.
+   This eliminates having to specify common parameters:
+
+.. code-block:: python
+
+  config_file_path = "<path_to_your_config_file">
+  gem_using_config_file = Gem(user_name="Mantid2", config_file=config_file_path)
+
+3. Using a combination of both, a parameter set from the script will override the
+   configuration parameter without changing the configuration file.
+
+.. code-block:: python
+
+  # This will use "My custom location" instead of the value set in the configuration file
+  gem_overriden = Gem(user_name="Mantid3", config_file=config_file_path,
+                      output_directory="My custom location")
+
+
+Vanadium Calibration
+--------------------
+Within the objects now configured we can run the vanadium calibrations. This
+is done with the `create_vanadium` method.
+
+This will generate a calibration for the matching vanadium and empty runs in
+the calibration mapping file (see :ref:`gem_calibration_map-powder-diffraction-ref`)
+and store it into the calibration folder under the appropriate label.
+
+*Note: This only needs to be completed once per cycle for each set of options used.
+The splined vanadium will automatically be loaded during focusing so the
+vanadium calibration step should not be part of your focusing scripts.*
+
+TODO the following parameters are needed.
+
+.. code-block:: python
+
+  # Using the manually specified object where we put in the calibration folder
+  # location when configuring the scripts
+  gem_manually_specified.create_vanadium(run_in_range="123", ...)
+
+Focusing
+---------
+Using the examples for the configured scripts we can now run the focusing method:
+
+TODO required parameters
+
+.. code-block:: python
+
+  # We will use the object which has the output_directory overridden to
+  # "My custom location"
+  gem_overriden.focus(run_number="140-150", input_mode="Individual"...)
+
diff --git a/docs/source/api/python/techniques/ISISPowder-Polaris-v1.rst b/docs/source/api/python/techniques/ISISPowder-Polaris-v1.rst
index 5a060373c686cb77767fe05f6dddd34b09398078..55fbb7b6d7a47588ea5f25445bf002cf8e6a2665 100644
--- a/docs/source/api/python/techniques/ISISPowder-Polaris-v1.rst
+++ b/docs/source/api/python/techniques/ISISPowder-Polaris-v1.rst
@@ -26,10 +26,10 @@ must be present:
   offsets for that cycle
 
 The names of the .cal grouping file and masking file are set in the advanced
-configuration file. See: TODO link
+configuration file. See: :ref:`polaris_adv_config-powder-diffraction-ref`
 
 The label for the run being processed and the appropriate offset filename is
-read from the calibration mapping file: TODO link
+read from the calibration mapping file: :ref:`polaris_calibration_map-powder-diffraction-ref`
 
 .. _polaris_calibration_map-powder-diffraction-ref:
 
@@ -101,10 +101,6 @@ For background on script parameters and how they are evaluated see:
   in a cylindrical sample as defined in the advanced configuration file. It then applies
   these calibrations to the vanadium sample.
 
-  If set to true during focusing the vanadium with these corrections is loaded
-  and used, if false it will load a vanadium sample where these corrections have
-  not been applied.
-
 - `do_van_normalisation` - If set to True divides the sample by the calculated vanadium
   spline during the normalisation step.
 
@@ -128,6 +124,8 @@ For background on script parameters and how they are evaluated see:
 
 - `user_name` - Specifies the user name to use when saving out focused data.
 
+.. _polaris_adv_config-powder-diffraction-ref:
+
 Advanced Script Parameters
 --------------------------
 
diff --git a/docs/source/api/python/techniques/ISISPowder-v1.rst b/docs/source/api/python/techniques/ISISPowder-v1.rst
index 6fab89440c713a263ae229d3509e8d7e01e58a5f..c0775c443e86c6ae81f0c73ddbd0e4b34332b3d9 100644
--- a/docs/source/api/python/techniques/ISISPowder-v1.rst
+++ b/docs/source/api/python/techniques/ISISPowder-v1.rst
@@ -12,11 +12,6 @@ ISIS Powder Diffraction Scripts
     :local:
 
 
-Instrument Specific Documentation
----------------------------------
-- :ref:`isis-powder-diffraction-pearl-ref`
-- :ref:`isis-powder-diffraction-polaris-ref`
-
 
 Overview and General Information
 --------------------------------
@@ -26,6 +21,14 @@ their individual requirements. At the most fundamental level it provides the
 functionality to calculate and apply vanadium calibrations and subsequently
 apply these corrections to experimental data.
 
+.. _instrument_doc_links_isis-powder-diffraction-ref:
+
+Instrument Specific Documentation
+---------------------------------
+- :ref:`isis-powder-diffraction-gem-ref`
+- :ref:`isis-powder-diffraction-pearl-ref`
+- :ref:`isis-powder-diffraction-polaris-ref`
+
 
 Data Files Setup
 ^^^^^^^^^^^^^^^^^
@@ -91,7 +94,7 @@ Calibration Configuration File
 The calibration mapping file allows users to specify ranges of runs and their
 common properties to all of them. These include the vanadium and empty run numbers,
 offset file and label for those runs. Each format is bespoke to the instrument's
-requirements and is documented as part of the instrument documentation.
+requirements and is documented as part of the :ref:`instrument_doc_links_isis-powder-diffraction-ref`
 
 - The first line in all examples holds the run numbers.
 - This is the range of runs inclusively for example *123-130*
diff --git a/scripts/Diffraction/isis_powder/polaris_routines/polaris_algs.py b/scripts/Diffraction/isis_powder/polaris_routines/polaris_algs.py
index 77824e200badf4df5d0e14d90159fa188f573ffd..664e4df0a4fcd62e2d4e2f7c1bd6af4dc9bbd885 100644
--- a/scripts/Diffraction/isis_powder/polaris_routines/polaris_algs.py
+++ b/scripts/Diffraction/isis_powder/polaris_routines/polaris_algs.py
@@ -49,7 +49,7 @@ def get_run_details(run_number_string, inst_settings):
     offsets_file_full_path = os.path.join(in_calib_dir, offset_file_name)
 
     # Generate the name of the splined file we will either be loading or saving
-    chopper_status = "On" if inst_settings.chopper_on else "Off"
+    chopper_status = "ChopperOn" if inst_settings.chopper_on else "ChopperOff"
     splined_vanadium_name = common.generate_splined_name(vanadium_runs, chopper_status, offset_file_name)
 
     splined_vanadium = os.path.join(in_calib_dir, splined_vanadium_name)