Not totally portable. They have built some ctags option dependencies that I'm going to have to futz with in order to get the makefile to run.

    12:58 shephard:c shephard$ make all
    ctags -R .
    ctags: illegal option -- R
    usage: ctags [-BFadtuwvx] [-f tagsfile] file ...
    make: *** [tags] Error 1

[Edit - No "-R" option for ctags in OS X 10.8.5, or in OpenBSD Current - http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man1/...

Edit2 - Now, it seems to be breaking on lemon not being explicitly called out in the path during a make:

  lemon filter_dsl_parse.y
  make[1]: lemon: No such file or directory
  make[1]: *** [filter_dsl_parse.c] Error 1
  make: *** [dsls] Error 2
  13:07 shephard:c shephard$

]

He says he used GNU C99, how is that portable C?

http://johnkerl.org/miller/doc/whyc.html#C_is_old-school