Scalable way to manage configuration flags

[Heime]

To pass set makeinfo options using a makefile, I have included
the css and split variables in my makefile.

For html there exist other makeinfo options, like --css-ref=URL,
--internal-links=FILE, --transliterate-file-names, and --node-files.

To add these as user otpions, would I similarly add a corresponding
variable for each?

ifneq ($(css),)
        css = --css-include=$(css)
endif

ifneq ($(split),)
        split = --split=$(split)
endif


.PHONY: split-chapter split-section split-node

split-chapter: split=--split=chapter
split-section: split=--split=section
split-node: split=--split=node

split-chapter split-section split-node: $(hmldir)/antares.html

.SECONDEXPANSION:  # Enable second expansion of $(@D)

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