diff --git a/script/graphs/README.rst b/script/graphs/README.rst
index 10724cb..f9db4a1 100644
--- a/script/graphs/README.rst
+++ b/script/graphs/README.rst
@@ -18,4 +18,23 @@
 
     bash categorize-tests.bash juno > juno-tests.png 2> juno-tests.txt
 
+Lines of Code by Module
+-----------------------
+
+The script `sloc-viz.bash`, and its associated plot script, generate a stacked
+bar chart where each bar is a module and the bars' segments represent programming
+languages (or documentation languages). This script will produce a graph for
+whatever directory it's run within, and has special logic that includes more
+detail when run from the Trusted Firmware - A project's root directory.
+
+This script has additional requirements:
+* ``tokei`` - a quick source lines of code counting tool
+* ``jq`` - a JSON query language for the command line, version 1.6 or later
+  as the ``--jsonargs`` option is required
+
+For example, when run from the root of TF-A, the following commandline will graph
+sloc of TF-A:
+
+    bash ../<this-repo>/script/graph/sloc-viz.bash > sloc.png 2> sloc.tsv
+
 *Copyright (c) 2021, Arm Limited. All rights reserved.*