User-configurable HTML splitting

I want to include the ability for users to split by chapter,=20
section, or node when outputting the html documentation.

Variable OPTS is used as a general options not specific to html. =20
With other html specific options stored in a different variable.

makeinfo has the --split=3Dchapter, --split=3D section, and=20
--split=3D node to do this.  How can I include this functionality=20
for users of my makefile?=20


opts =3D --force --enable-encoding -I ${srcdir}
hmlopts =3D --split=3Dchapter # section, node


srcs =3D ${srcdir}/antares.texi

.PHONY: html
html: ${hmldir}/antares.html

.SECONDEXPANSION:
$(hmldir)/antares.html: $(srcs) | $$(@D)
=09makeinfo $(opts) --html -o $@ $<