DOCS := $(patsubst %.txt,%,$(wildcard *.txt */*.txt))

html: xref_en.links $(patsubst %,%.html,$(DOCS))

%.html: %.txt
	asciidoc -a linksfile=xref_en.links -a stylesheet=$(shell pwd)/linuxcnc.css -f xhtml11.conf -d book -a toc -a numbered -b xhtml11 $< || (X=$$?; rm $@; exit $$X)