-DOCFILE=${DOCFILE_BASE}.${DOCFILE_EXT}
-FOFILE=${DOCFILE_BASE}.fo
-PDFFILE=${DOCFILE_BASE}.pdf
-PSFILE=${DOCFILE_BASE}.ps
-DVIFILE=${DOCFILE_BASE}.dvi
-TXTFILE=${DOCFILE_BASE}.txt
-TMPFILES=${DOCFILE_BASE}.aux ${DOCFILE_BASE}.out ${DOCFILE_BASE}.log
-DOCFILES=$(shell echo *.xml)
+DOCFILE:=${DOCFILE_BASE}.${DOCFILE_EXT}
+FOFILE:=${DOCFILE_BASE}.fo
+PDFFILE:=${DOCFILE_BASE}.pdf
+PSFILE:=${DOCFILE_BASE}.ps
+DVIFILE:=${DOCFILE_BASE}.dvi
+TXTFILE:=${DOCFILE_BASE}.txt
+TMPFILES:=${DOCFILE_BASE}.aux ${DOCFILE_BASE}.out ${DOCFILE_BASE}.log
+DOCFILES:=$(shell echo *.xml)
+
+CHECK:=xmllint --noout --catalogs --xinclude --postvalid $(DOCFILE) || exit 1