diff --git a/make-includes/build_content_rules.make b/make-includes/build_content_rules.make
index d8b302e..32dff99 100755
--- a/make-includes/build_content_rules.make
+++ b/make-includes/build_content_rules.make
@@ -95,7 +95,7 @@
 # Build EPS from Inkscape SVG source.
 #
 %.eps: %.svg
-	inkscape --file=$< --export-text-to-path --without-gui --export-eps=$@
+	$(INKSCAPE) --file=$< --export-text-to-path --without-gui --export-eps=$@
 
 
 ################################################################################
@@ -135,14 +135,14 @@
 #   appears to have been fixed in GhostScript 8.51?
 #
 %-print.pdf: %.eps
-	@announce "Generating $@ (print)"
-	@ps2eps --ignoreBB --nohires --loose --gsbbox < $< | ps2pdf -dEPSCrop - $@
-	@mv $@ $(BUILD_DIR)
+	@$(ANNOUNCE) "Generating $@ (print)"
+	@$(PS2EPS) --ignoreBB --nohires --loose --gsbbox < $< | $(PS2PDF) -dEPSCrop - $@
+	@$(MV) $@ $(BUILD_DIR)
 
 %-print.pdf: %.ps
-	@announce "Generating $@ (print)"
-	@ps2eps --ignoreBB --nohires --loose --gsbbox < $< | ps2pdf -dEPSCrop - $@
-	@mv $@ $(BUILD_DIR)
+	@$(ANNOUNCE) "Generating $@ (print)"
+	@$(PS2EPS) --ignoreBB --nohires --loose --gsbbox < $< | $(PS2PDF) -dEPSCrop - $@
+	@$(MV) $@ $(BUILD_DIR)
 
 
 ################################################################################
@@ -162,55 +162,55 @@
 # Build 96 DPI version for normal web display
 #
 %-web.png: %.eps
-	@announce "Generating $@ (web)"
-	@ps2eps --ignoreBB --nohires --loose --gsbbox < $< | \
-		gs -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r96 \
+	@$(ANNOUNCE) "Generating $@ (web)"
+	@$(PS2EPS) --ignoreBB --nohires --loose --gsbbox < $< | \
+		$(GS) -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r96 \
 		-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile=$@ -
-	@mv $@ $(BUILD_DIR)
+	@$(MV) $@ $(BUILD_DIR)
 
 %-web.png: %.ps
-	@announce "Generating $@ (web)"
-	@ps2eps --ignoreBB --nohires --loose --gsbbox < $< | \
-		gs -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r96 \
+	@$(ANNOUNCE) "Generating $@ (web)"
+	@$(PS2EPS) --ignoreBB --nohires --loose --gsbbox < $< | \
+		$(GS) -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r96 \
 		-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile=$@ -
-	@mv $@ $(BUILD_DIR)
+	@$(MV) $@ $(BUILD_DIR)
 
 %-web.png: %.pdf
-	@announce "Generating $@ (web)"
-	gs -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -r96 \
+	@$(ANNOUNCE) "Generating $@ (web)"
+	$(GS) -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -r96 \
 		-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile=$@ $<
-	@mv $@ $(BUILD_DIR)
+	@$(MV) $@ $(BUILD_DIR)
 #
 # Build 144 DPI version for zoomed web display
 #
 %-web-zoom.png: %.eps
-	@announce "Generating $@ (zoomed web)"
-	@ps2eps --ignoreBB --nohires --loose --gsbbox < $< | \
-		gs -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r144 \
+	@$(ANNOUNCE) "Generating $@ (zoomed web)"
+	@$(PS2EPS) --ignoreBB --nohires --loose --gsbbox < $< | \
+		$(GS) -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r144 \
 		-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile=$@ -
-	@mv $@ $(BUILD_DIR)
+	@$(MV) $@ $(BUILD_DIR)
 
 %-web-zoom.png: %.ps
-	@announce "Generating $@ (zoomed web)"
-	@ps2eps --ignoreBB --nohires --loose --gsbbox < $< | \
-		gs -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r144 \
+	@$(ANNOUNCE) "Generating $@ (zoomed web)"
+	@$(PS2EPS) --ignoreBB --nohires --loose --gsbbox < $< | \
+		$(GS) -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r144 \
 		-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile=$@ -
-	@mv $@ $(BUILD_DIR)
+	@$(MV) $@ $(BUILD_DIR)
 
 %-web-zoom.png: %.pdf
-	@announce "Generating $@ (zoomed web)"
-	gs -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -r144 \
+	@$(ANNOUNCE) "Generating $@ (zoomed web)"
+	$(GS) -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -r144 \
 		-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile=$@ $<
-	@mv $@ $(BUILD_DIR)
+	@$(MV) $@ $(BUILD_DIR)
 
 #
 # Are 600 DPI versions even needed?? They don't seem to be used anywhere...
 #
 # %-web-hires.png: %.eps
-# 	@announce "Generating $@ (600 dpi)"
-# 	@gs -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r600 \
+# 	@$(ANNOUNCE) "Generating $@ (600 dpi)"
+# 	@$(GS) -q -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dEPSCrop -r600 \
 # 		-dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sOutputFile=$@ $<
-# 	@mv $@ $(BUILD_DIR)
+# 	@$(MV) $@ $(BUILD_DIR)
 
 
 ################################################################################
@@ -223,12 +223,12 @@
 # natively.
 #
 %-print.png: %.png
-	@announce "Generating $@ (print)"
-	@cp $< $(BUILD_DIR)/$@
+	@$(ANNOUNCE) "Generating $@ (print)"
+	@$(CP) $< $(BUILD_DIR)/$@
 
 %-web.png: %.png
-	@announce "Generating $@ (web)"
-	@cp $< $(BUILD_DIR)/$@
+	@$(ANNOUNCE) "Generating $@ (web)"
+	@$(CP) $< $(BUILD_DIR)/$@
 
 
 ################################################################################
@@ -238,8 +238,8 @@
 # we just copy the original file to the build directory.
 #
 %-print.pdf: %.pdf
-	@announce "Generating $@ (print)"
-	@cp $< $(BUILD_DIR)/$@
+	@$(ANNOUNCE) "Generating $@ (print)"
+	@$(CP) $< $(BUILD_DIR)/$@
 
 
 ################################################################################
@@ -252,10 +252,10 @@
 # clean: web-clean print-clean
 # 
 # web-clean:
-# 	rm -f *.png
+# 	$(RM) -f *.png
 # 
 # print-clean:
-# 	rm -f *.pdf
+# 	$(RM) -f *.pdf
 
 
 ################################################################################
@@ -263,12 +263,12 @@
 # Debugging information, mostly lists of the generated variables.
 #
 debug:
-	@announce Externally defined variables
-	@echo "TEACHING_SHARED = [$(TEACHING_SHARED)]"
-	@echo "BUILD_DIR = [$(BUILD_DIR)]"
-	@announce Internally defined variables
-	@echo "GLOBAL_HANDBOOK_INCLUDE = [$(GLOBAL_HANDBOOK_INCLUDE)]"
-	@echo "LOCAL_HANDBOOK_INCLUDE = [$(LOCAL_HANDBOOK_INCLUDE)]"
+	@$(ANNOUNCE) Externally defined variables
+	@$(ECHO) "TEACHING_SHARED = [$(TEACHING_SHARED)]"
+	@$(ECHO) "BUILD_DIR = [$(BUILD_DIR)]"
+	@$(ANNOUNCE) Internally defined variables
+	@$(ECHO) "GLOBAL_HANDBOOK_INCLUDE = [$(GLOBAL_HANDBOOK_INCLUDE)]"
+	@$(ECHO) "LOCAL_HANDBOOK_INCLUDE = [$(LOCAL_HANDBOOK_INCLUDE)]"
 
 
 ################################################################################
@@ -276,4 +276,4 @@
 # Print out the list of targets. Handy for when you forget!
 #
 targets:
-	@echo $(TARGETS)
+	@$(ECHO) $(TARGETS)