diff --git a/doc/src/Developer.rst b/doc/src/Developer.rst
index b0cfcc14fc..d4afd6f298 100644
--- a/doc/src/Developer.rst
+++ b/doc/src/Developer.rst
@@ -24,4 +24,5 @@ of time and requests from the LAMMPS user community.
    Classes
    Developer_platform
    Developer_utils
+   Developer_internal
    Developer_grid
diff --git a/doc/src/Developer_internal.rst b/doc/src/Developer_internal.rst
new file mode 100644
index 0000000000..5a134a8b32
--- /dev/null
+++ b/doc/src/Developer_internal.rst
@@ -0,0 +1,113 @@
+
+Internal Styles
+---------------
+
+LAMMPS has a number of styles that are not meant to be used in an input
+file and thus are not documented in the :doc:`LAMMPS command
+documentation <Commands_all>`.  The differentiation between user
+commands and internal commands is through the case of the command name:
+user commands and styles are all lower case, internal styles are all
+upper case.  Internal styles are not called from the input file, but
+their classes are instantiated by other styles.  Often they are
+created by other styles to store internal data or to perform actions
+regularly at specific steps of the simulation.
+
+The paragraphs below document some of those styles that have general
+utility and may be used to avoid redundant implementation.
+
+DEPRECATED Styles
+^^^^^^^^^^^^^^^^^
+
+The styles called DEPRECATED (e.g. pair, bond, fix, compute, region, etc.)
+have the purpose to inform users that a specific style has been removed
+or renamed.  This is achieved by creating an alias for the deprecated
+style to the corresponding class.  For example, the fix style DEPRECATED
+is aliased to fix style ave/spatial and fix style ave/spatial/sphere with
+the following code:
+
+.. code-block:: c++
+
+   FixStyle(DEPRECATED,FixDeprecated);
+   FixStyle(ave/spatial,FixDeprecated);
+   FixStyle(ave/spatial/sphere,FixDeprecated);
+
+The individual class will then determine based on the style name
+what action to perform:
+
+- inform that the style has been removed and what style replaces it, if any, and then error out
+- inform that the style has been renamed and then either execute the replacement or error out
+- inform that the style is no longer required, and it is thus ignored and continue
+
+There is also a section in the user's guide for :doc:`removed commands
+and packages <Commands_removed>` with additional explanations.
+
+Internal fix styles
+^^^^^^^^^^^^^^^^^^^
+
+fix DUMMY
+"""""""""
+
+Most fix classes cannot be instantiated before the simulation box has
+been created since they access data that is only available then.
+However, in some cases it is required that a fix must be at or close to
+the top of the list of all fixes.  In those cases an instance of the
+DUMMY fix style may be created by calling ``Modify::add_fix()`` and then
+later replaced by calling ``Modify::replace_fix()``.
+
+fix STORE/ATOM
+""""""""""""""
+
+Fix STORE/ATOM can be used as persistent storage of per-atom data.
+
+**Syntax**
+
+.. code-block:: LAMMPS
+
+   fix ID group-ID STORE/ATOM N1 N2 gflag rflag
+
+* ID, group-ID are documented in :doc:`fix <fix>` command
+* STORE/ATOM = style name of this fix command
+* N1 = 1, N2 = 0 : data is per-atom vector = single value per atom
+* N1 > 1, N2 = 0 : data is per-atom array = N1 values per atom
+* N1 > 0, N2 > 0 : data is per-atom tensor = N1xN2 values per atom
+* gflag = 1 communicate per-atom values with ghost atoms, 0 update ghost atoms
+* rflag = 1 store per-atom value in restart file, 0 do not store data in restart
+
+Similar functionality is also available through using custom per-atom
+properties with :doc:`fix property/atom <fix_property_atom>`.  The
+choice between the two fixes should be based on whether the user should
+be able to access this per-atom data: if yes, then fix property/atom is
+preferred, otherwise fix STORE/ATOM.
+
+fix STORE/GLOBAL
+""""""""""""""""
+
+Fix STORE/GLOBAL can be used as persistent storage of global data with support for restarts
+
+**Syntax**
+
+.. code-block:: LAMMPS
+
+   fix ID group-ID STORE/GLOBAL N1 N2
+
+* ID, group-ID are documented in :doc:`fix <fix>` command
+* STORE/GLOBAL = style name of this fix command
+* N1 >=1 : number of global items to store
+* N2 = 1 : data is global vector of length N1
+* N2 > 1 : data is global N1xN2 array
+
+fix STORE/LOCAL
+"""""""""""""""
+
+Fix STORE/LOCAL can be used as persistent storage for local data
+
+**Syntax**
+
+.. code-block:: LAMMPS
+
+   fix ID group-ID STORE/LOCAL Nreset Nvalues
+
+* ID, group-ID are documented in :doc:`fix <fix>` command
+* STORE/LOCAL = style name of this fix command
+* Nreset = frequency at which local data is available
+* Nvalues = number of values per local item, that is the number of columns
diff --git a/doc/utils/sphinx-config/false_positives.txt b/doc/utils/sphinx-config/false_positives.txt
index f94d528cfe..517748825c 100644
--- a/doc/utils/sphinx-config/false_positives.txt
+++ b/doc/utils/sphinx-config/false_positives.txt
@@ -1321,6 +1321,7 @@ geturl
 gewald
 Gezelter
 gfile
+gflag
 Gflop
 gfortran
 ghostneigh
@@ -3250,6 +3251,7 @@ rewrap
 rezwanur
 rfac
 rfile
+rflag
 rg
 Rg
 Rhaphson