diff --git a/.gitmodules b/.gitmodules
index 6922aea9..e1b8fe48 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -14,3 +14,15 @@
 	path = dependencies/CASE-unstable-2.0.0
 	url = https://github.com/casework/CASE-Archive.git
 	branch = unstable-2.0.0
+[submodule "dependencies/CDO-Shapes-BFO"]
+	path = dependencies/CDO-Shapes-BFO
+	url = https://github.com/Cyber-Domain-Ontology/CDO-Shapes-BFO.git
+	branch = main
+[submodule "dependencies/CDO-Shapes-Time"]
+	path = dependencies/CDO-Shapes-Time
+	url = https://github.com/Cyber-Domain-Ontology/CDO-Shapes-Time.git
+	branch = main
+[submodule "dependencies/CDO-Shapes-gufo"]
+	path = dependencies/CDO-Shapes-gufo
+	url = https://github.com/Cyber-Domain-Ontology/CDO-Shapes-gufo.git
+	branch = main
diff --git a/Makefile b/Makefile
index 23738d53..e8d9d616 100644
--- a/Makefile
+++ b/Makefile
@@ -61,6 +61,21 @@ all: \
 	$(MAKE) \
 	  --directory dependencies/CASE-unstable-2.0.0 \
 	  .git_submodule_init.done.log
+	# CDO-Shapes-BFO
+	test -r dependencies/CDO-Shapes-BFO/README.md \
+	  || git submodule update --init dependencies/CDO-Shapes-BFO
+	test -r dependencies/CDO-Shapes-BFO/README.md \
+	  || (echo "ERROR:Makefile:CDO-Shapes-BFO submodule README.md file not found, even though CDO-Shapes-BFO submodule initialized." >&2 ; exit 2)
+	# CDO-Shapes-Time
+	test -r dependencies/CDO-Shapes-Time/README.md \
+	  || git submodule update --init dependencies/CDO-Shapes-Time
+	test -r dependencies/CDO-Shapes-Time/README.md \
+	  || (echo "ERROR:Makefile:CDO-Shapes-Time submodule README.md file not found, even though CDO-Shapes-Time submodule initialized." >&2 ; exit 2)
+	# CDO-Shapes-gufo
+	test -r dependencies/CDO-Shapes-gufo/README.md \
+	  || git submodule update --init dependencies/CDO-Shapes-gufo
+	test -r dependencies/CDO-Shapes-gufo/README.md \
+	  || (echo "ERROR:Makefile:CDO-Shapes-gufo submodule README.md file not found, even though CDO-Shapes-gufo submodule initialized." >&2 ; exit 2)
 	# Retrieve rdf-toolkit.jar.
 	$(MAKE) \
 	  --directory dependencies/CASE-develop \
diff --git a/dependencies/CDO-Shapes-BFO b/dependencies/CDO-Shapes-BFO
new file mode 160000
index 00000000..b25016e8
--- /dev/null
+++ b/dependencies/CDO-Shapes-BFO
@@ -0,0 +1 @@
+Subproject commit b25016e8587375625c521ce3e080fcde074c1d09
diff --git a/dependencies/CDO-Shapes-Time b/dependencies/CDO-Shapes-Time
new file mode 160000
index 00000000..6a5a0b62
--- /dev/null
+++ b/dependencies/CDO-Shapes-Time
@@ -0,0 +1 @@
+Subproject commit 6a5a0b624922cacf941b48b9d89959f1b9b6e4c3
diff --git a/dependencies/CDO-Shapes-gufo b/dependencies/CDO-Shapes-gufo
new file mode 160000
index 00000000..9a41df1b
--- /dev/null
+++ b/dependencies/CDO-Shapes-gufo
@@ -0,0 +1 @@
+Subproject commit 9a41df1bad2e1ce935c1cc42721c9f696a4174eb
diff --git a/examples/illustrations/existence_intervals/postvisit.mk b/examples/illustrations/existence_intervals/postvisit.mk
new file mode 100644
index 00000000..0145b87e
--- /dev/null
+++ b/examples/illustrations/existence_intervals/postvisit.mk
@@ -0,0 +1,55 @@
+#!/usr/bin/make -f
+
+# Portions of this file contributed by NIST are governed by the
+# following statement:
+#
+# This software was developed at the National Institute of Standards
+# and Technology by employees of the Federal Government in the course
+# of their official duties. Pursuant to Title 17 Section 105 of the
+# United States Code, this software is not subject to copyright
+# protection within the United States. NIST assumes no responsibility
+# whatsoever for its use by other parties, and makes no guarantees,
+# expressed or implied, about its quality, reliability, or any other
+# characteristic.
+#
+# We would appreciate acknowledgement if the software is used.
+
+SHELL := /bin/bash
+
+top_srcdir := $(shell cd ../../.. ; pwd)
+
+bfo_ttl := $(top_srcdir)/dependencies/CDO-Shapes-BFO/dependencies/BFO.ttl
+sh_bfo_ttl := $(top_srcdir)/dependencies/CDO-Shapes-BFO/shapes/sh-bfo.ttl
+
+gufo_ttl := $(top_srcdir)/dependencies/CDO-Shapes-gufo/dependencies/gufo.ttl
+sh_gufo_ttl := $(top_srcdir)/dependencies/CDO-Shapes-gufo/shapes/sh-gufo.ttl
+
+time_ttl := $(top_srcdir)/dependencies/CDO-Shapes-Time/dependencies/time.ttl
+sh_time_ttl := $(top_srcdir)/dependencies/CDO-Shapes-Time/shapes/sh-time.ttl
+
+all:
+
+.cdo-shapes.done.log: \
+  $(bfo_ttl) \
+  $(gufo_ttl) \
+  $(sh_bfo_ttl) \
+  $(sh_gufo_ttl) \
+  $(sh_time_ttl) \
+  $(time_ttl) \
+  $(top_srcdir)/.venv.done.log \
+  existence_intervals.json
+	source $(top_srcdir)/venv/bin/activate \
+	  && case_validate \
+	    --ontology-graph $(bfo_ttl) \
+	    --ontology-graph $(gufo_ttl) \
+	    --ontology-graph $(sh_bfo_ttl) \
+	    --ontology-graph $(sh_gufo_ttl) \
+	    --ontology-graph $(sh_time_ttl) \
+	    --ontology-graph $(time_ttl) \
+	    existence_intervals.json
+	touch $@
+
+check: \
+  .cdo-shapes.done.log
+
+clean:
diff --git a/examples/illustrations/src/illustration-nosrc.mk b/examples/illustrations/src/illustration-nosrc.mk
index bc4d63ff..52f52ed5 100644
--- a/examples/illustrations/src/illustration-nosrc.mk
+++ b/examples/illustrations/src/illustration-nosrc.mk
@@ -85,6 +85,9 @@ all: \
 	test ! -r figures/Makefile \
 	  || $(MAKE) \
 	    --directory figures
+	test ! -r postvisit.mk \
+	  || $(MAKE) \
+	    --file postvisit.mk
 
 .PHONY: \
   check-pytest
@@ -335,6 +338,10 @@ check: \
   $(example_name)_validation-develop-2.0.0.ttl \
   $(example_name)_validation-unstable.ttl \
   $(example_name)_validation-unstable-2.0.0.ttl
+	test ! -r postvisit.mk \
+	  || $(MAKE) \
+	    --file postvisit.mk \
+	    check
 
 # Run pytest tests only if any are written.
 # (Pytest exits in an error state if called with no tests found.)
@@ -348,6 +355,10 @@ check-pytest: \
 	  )
 
 clean:
+	@test ! -r postvisit.mk \
+	  || $(MAKE) \
+	    --file postvisit.mk \
+	    clean
 	@rm -f \
 	  .drafting.ttl.*.log \
 	  figures/*.dot \