diff --git a/make-includes/build_lecture_rules.make b/make-includes/build_lecture_rules.make
index f01fe8f..ae0aec5 100755
--- a/make-includes/build_lecture_rules.make
+++ b/make-includes/build_lecture_rules.make
@@ -12,10 +12,9 @@
 
 ################################################################################
 #
-# Standard file suffixes.
+# Add standard file suffixes.
 #
-.SUFFIXES:
-.SUFFIXES: .pdf .tex .graffle .png .tif .plo
+.SUFFIXES: .pdf .tex .dvi .graffle .png .tif .plo .jpg .pict
 
 
 ################################################################################
@@ -33,30 +32,17 @@
 vpath %.pdf $(IMGDIR)
 vpath %.png $(IMGDIR)
 vpath %.tif $(IMGDIR)
+vpath %.jpg $(IMGDIR)
 vpath %.plo $(IMGDIR)
 
 
 ################################################################################
 #
-# Standard file list variables.
-#
-# List of images used in the presentation as actual content.
-#
-SLIDE_IMAGES=
-#
-# List of images used in the presentation as backgrounds or watermarks.
-#
-SLIDE_BACKGROUNDS=
-#
-# List of images used in the figures and examples document.
-#
-FIG_IMAGES=
-#
 # Files to be cleaned by the various "clean" targets.
 #
-TIDY_FILES=*.tmp *.aux *.out *.log *.nav *.toc *.snm *.head *.dvi \
+TIDY_FILES+=*.tmp *.aux *.out *.log *.nav *.toc *.snm *.head *.dvi \
 	slides-combined.pdf slides-notes.pdf
-CLEAN_FILES=*.pdf
+CLEAN_FILES+=*.pdf
 
 
 ################################################################################
@@ -67,9 +53,9 @@
 #
 DRAFT=
 #
-# Specify LaTeX document options (comma-separated list)
+# Specify LaTeX document options (comma-separated list).
 #
-LATEX_OPTS=pdftex,usepdftitle=false,$(DRAFT)
+LATEX_OPTS+=pdftex,usepdftitle=false,$(DRAFT)
 #
 # Base file names for the various documents.
 #
@@ -80,7 +66,7 @@
 #
 # List of standard "phony" build targets.
 #
-TARGETS=all slides notes slides-combined slides-notes figures combined \
+TARGETS+=all slides notes slides-combined slides-notes figures combined \
 	debug test clean tidy targets
 #
 .PHONY: $(TARGETS)
@@ -101,11 +87,16 @@
 all: slides notes figures combined
 
 
-ifneq ($(strip $(SLIDES)),)
 ################################################################################
 #
+# Build presentation slides. If $(SLIDES) is empty, these rules are ignored.
+#
+ifneq ($(strip $(SLIDES)),)
+
+#
 # Set the prerequisites for the "slides" build target, depending on
-# whether the figures document exists.
+# whether the figures document exists. If $(FIGURES) is non-empty, we need
+# to include the figures .aux file for inter-document cross-references.
 #
 ifeq ($(strip $(FIGURES)),)
 SLIDES_PREREQS:=$(SLIDES).pdf
@@ -113,15 +104,12 @@
 SLIDES_PREREQS:=figures $(SLIDES).pdf
 endif
 
-################################################################################
 #
-# Build the slides for the presentation. Include the figures .aux file for
-# inter-document cross-references, but only if $(FIGURES) is non-empty. If
-# $(SLIDES) is empty, these rules are ignored.
+# Build the slides for the presentation.
 #
 slides: $(SLIDES_PREREQS)
 
-$(SLIDES).pdf: $(SLIDES).tex $(SLIDE_IMAGES)
+$(SLIDES).pdf: $(SLIDES).tex $(SLIDE_IMAGES) $(SLIDE_BACKGROUNDS)
 	pdflatex --jobname=$(SLIDES) '\documentclass[$(LATEX_OPTS)]{beamer}\input{$(SLIDES)}'
 	pdflatex --jobname=$(SLIDES) '\documentclass[$(LATEX_OPTS)]{beamer}\input{$(SLIDES)}'
 
@@ -133,22 +121,24 @@
 endif
 
 
-ifneq ($(strip $(NOTES)),)
 ################################################################################
 #
-# Build the slides with notes. If $(NOTES) is empty, these rules are
+# Build the presentation notes. If $(NOTES) is empty, these rules are
 # ignored.
 #
+ifneq ($(strip $(NOTES)),)
+
+#
+# Build the slides with notes.
+#
 slides-notes: slides-notes.pdf
 
-slides-notes.pdf: $(SLIDES).tex $(SLIDE_IMAGES)
+slides-notes.pdf: $(SLIDES).tex $(SLIDE_IMAGES) $(SLIDE_BACKGROUNDS)
 	pdflatex --jobname=slides-notes '\documentclass[$(LATEX_OPTS),notes=onlyslideswithnotes]{beamer}\input{$(SLIDES)}'
 	pdflatex --jobname=slides-notes '\documentclass[$(LATEX_OPTS),notes=onlyslideswithnotes]{beamer}\input{$(SLIDES)}'
 
-################################################################################
 #
-# Build the slides with notes, 6-up. If $(NOTES) is empty, these rules are
-# ignored.
+# Build the slides with notes, 6-up.
 #
 notes: $(NOTES).pdf
 
@@ -163,11 +153,17 @@
 endif
 
 
-ifneq ($(strip $(COMBINED)),)
 ################################################################################
 #
+# Build the complete combined lecture document. If $(COMBINED) is empty,
+# these rules are ignored.
+#
+ifneq ($(strip $(COMBINED)),)
+
+#
 # Set the prerequisites for the "combined" build target, depending on
-# whether the figures document exists.
+# whether the figures document exists. If $(FIGURES) is empty, they are
+# omitted from the combined document.
 #
 ifeq ($(strip $(FIGURES)),)
 COMBINED_PREREQS:=$(COMBINED).tex slides-combined.pdf
@@ -175,22 +171,17 @@
 COMBINED_PREREQS:=$(COMBINED).tex slides-combined.pdf $(FIGURES).pdf
 endif
 
-################################################################################
 #
-# Build the slides for the combined document. If $(COMBINED) is empty,
-# these rules are ignored.
+# Build the slides for the combined document.
 #
 slides-combined: slides-combined.pdf
 
-slides-combined.pdf: $(SLIDES).tex $(SLIDE_IMAGES)
+slides-combined.pdf: $(SLIDES).tex $(SLIDE_IMAGES) $(SLIDE_BACKGROUNDS)
 	pdflatex --jobname=slides-combined '\documentclass[$(LATEX_OPTS),handout]{beamer}\input{$(SLIDES)}'
 	pdflatex --jobname=slides-combined '\documentclass[$(LATEX_OPTS),handout]{beamer}\input{$(SLIDES)}'
 
-################################################################################
 #
-# Build the complete combined document. If $(COMBINED) is empty, these
-# rules are ignored. If $(FIGURES) is empty, they are omitted from the
-# combined document.
+# Build the complete combined document.
 #
 combined: $(COMBINED).pdf
 
@@ -206,15 +197,17 @@
 endif
 
 
-ifneq ($(strip $(FIGURES)),)
 ################################################################################
 #
-# Build the figures and examples document. If $(FIGURES) is empty,
-# these rules are ignored.
+# Build the figures and examples document. If $(FIGURES) is empty, these
+# rules are ignored.
 #
+ifneq ($(strip $(FIGURES)),)
+
 figures: $(FIGURES).pdf
 
-$(FIGURES).pdf:	$(FIGURES).tex $(FIG_IMAGES)
+$(FIGURES).pdf: $(FIGURES).tex $(FIG_IMAGES)
+	@echo $(FIG_IMAGES)
 	pdflatex $<
 	pdflatex $<