Re-write of eqn(7) parser and MathML output.

This adds parser-level support for the grammar described by the eqn
second-edition technical paper, "Typesetting Mathematics — User's Guide"
(Kernighan, Cherry).
The reason for this re-write is the grouping rules, which were not
possible given the existing implementation.
The re-write has also considerably simplified the HTML (and, if it ever
is completed, terminal) front-end.

9 files changed, 894 insertions, 789 deletions

diff --git a/TODO b/TODO
index 5763e6f0..fbf1be4f 100644
--- a/TODO
+++ b/TODO
@@ -1,6 +1,6 @@
 ************************************************************************
 * Official mandoc TODO.
-* $Id: TODO,v 1.180 2014/10/06 18:35:49 schwarze Exp $
+* $Id: TODO,v 1.181 2014/10/10 08:44:24 kristaps Exp $
 ************************************************************************
 
 ************************************************************************
@@ -461,3 +461,9 @@ Several areas can be cleaned up to make mandoc even faster.  These are
    behaviour, which is not optimal.
  - Have Mac OSX systems automatically disable -static compilation of the
    CGI: -static isn't supported.
+
+************************************************************************
+* eqn missing features
+************************************************************************
+
+ - set, delim, fonts
diff --git a/eqn.7 b/eqn.7
index dcbad41c..ba8164c2 100644
--- a/eqn.7
+++ b/eqn.7
@@ -1,4 +1,4 @@
-.\"	$Id: eqn.7,v 1.29 2013/07/13 19:41:16 schwarze Exp $
+.\"	$Id: eqn.7,v 1.30 2014/10/10 08:44:24 kristaps Exp $
 .\"
 .\" Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: July 13 2013 $
+.Dd $Mdocdate: October 10 2014 $
 .Dt EQN 7
 .Os
 .Sh NAME
@@ -75,7 +75,6 @@ box     : text
         | \*qtdefine\*q text text
         | \*qgfont\*q text
         | \*qgsize\*q text
-        | \*qset\*q text text
         | \*qundef\*q text
         | box pos box
         | box mark
diff --git a/eqn.c b/eqn.c
index 7bb956d5..c2e7aed2 100644
--- a/eqn.c
+++ b/eqn.c
@@ -1,4 +1,4 @@
-/*	$Id: eqn.c,v 1.47 2014/09/28 14:05:11 kristaps Exp $ */
+/*	$Id: eqn.c,v 1.48 2014/10/10 08:44:24 kristaps Exp $ */
 /*
  * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -30,14 +30,111 @@
 #include "libmandoc.h"
 #include "libroff.h"
 
+#define	EQN_MSG(t, x) \
+	mandoc_msg((t), (x)->parse, (x)->eqn.ln, (x)->eqn.pos, NULL)
 #define	EQN_NEST_MAX	 128 /* maximum nesting of defines */
-#define	EQN_MSG(t, x)	 mandoc_msg((t), (x)->parse, (x)->eqn.ln, (x)->eqn.pos, NULL)
+#define	STRNEQ(p1, sz1, p2, sz2) \
+	((sz1) == (sz2) && 0 == strncmp((p1), (p2), (sz1)))
+#define	EQNSTREQ(x, p, sz) \
+	STRNEQ((x)->name, (x)->sz, (p), (sz))
 
-enum	eqn_rest {
-	EQN_DESCOPE,
-	EQN_ERR,
-	EQN_OK,
-	EQN_EOF
+enum	eqn_tok {
+	EQN_TOK_DYAD = 0,
+	EQN_TOK_VEC,
+	EQN_TOK_UNDER,
+	EQN_TOK_BAR,
+	EQN_TOK_TILDE,
+	EQN_TOK_HAT,
+	EQN_TOK_DOT,
+	EQN_TOK_DOTDOT,
+	EQN_TOK_FWD,
+	EQN_TOK_BACK,
+	EQN_TOK_DOWN,
+	EQN_TOK_UP,
+	EQN_TOK_FAT,
+	EQN_TOK_ROMAN,
+	EQN_TOK_ITALIC,
+	EQN_TOK_BOLD,
+	EQN_TOK_SIZE,
+	EQN_TOK_SUB,
+	EQN_TOK_SUP,
+	EQN_TOK_SQRT,
+	EQN_TOK_OVER,
+	EQN_TOK_FROM,
+	EQN_TOK_TO,
+	EQN_TOK_BRACE_OPEN,
+	EQN_TOK_BRACE_CLOSE,
+	EQN_TOK_GSIZE,
+	EQN_TOK_GFONT,
+	EQN_TOK_MARK,
+	EQN_TOK_LINEUP,
+	EQN_TOK_LEFT,
+	EQN_TOK_RIGHT,
+	EQN_TOK_PILE,
+	EQN_TOK_LPILE,
+	EQN_TOK_RPILE,
+	EQN_TOK_CPILE,
+	EQN_TOK_MATRIX,
+	EQN_TOK_CCOL,
+	EQN_TOK_LCOL,
+	EQN_TOK_RCOL,
+	EQN_TOK_DELIM,
+	EQN_TOK_DEFINE,
+	EQN_TOK_TDEFINE,
+	EQN_TOK_NDEFINE,
+	EQN_TOK_UNDEF,
+	EQN_TOK_EOF,
+	EQN_TOK_ABOVE,
+	EQN_TOK__MAX
+};
+
+static	const char *eqn_toks[EQN_TOK__MAX] = {
+	"dyad", /* EQN_TOK_DYAD */
+	"vec", /* EQN_TOK_VEC */
+	"under", /* EQN_TOK_UNDER */
+	"bar", /* EQN_TOK_BAR */
+	"tilde", /* EQN_TOK_TILDE */
+	"hat", /* EQN_TOK_HAT */
+	"dot", /* EQN_TOK_DOT */
+	"dotdot", /* EQN_TOK_DOTDOT */
+	"fwd", /* EQN_TOK_FWD * */
+	"back", /* EQN_TOK_BACK */
+	"down", /* EQN_TOK_DOWN */
+	"up", /* EQN_TOK_UP */
+	"fat", /* EQN_TOK_FAT */
+	"roman", /* EQN_TOK_ROMAN */
+	"italic", /* EQN_TOK_ITALIC */
+	"bold", /* EQN_TOK_BOLD */
+	"size", /* EQN_TOK_SIZE */
+	"sub", /* EQN_TOK_SUB */
+	"sup", /* EQN_TOK_SUP */
+	"sqrt", /* EQN_TOK_SQRT */
+	"over", /* EQN_TOK_OVER */
+	"from", /* EQN_TOK_FROM */
+	"to", /* EQN_TOK_TO */
+	"{", /* EQN_TOK_BRACE_OPEN */
+	"}", /* EQN_TOK_BRACE_CLOSE */
+	"gsize", /* EQN_TOK_GSIZE */
+	"gfont", /* EQN_TOK_GFONT */
+	"mark", /* EQN_TOK_MARK */
+	"lineup", /* EQN_TOK_LINEUP */
+	"left", /* EQN_TOK_LEFT */
+	"right", /* EQN_TOK_RIGHT */
+	"pile", /* EQN_TOK_PILE */
+	"lpile", /* EQN_TOK_LPILE */
+	"rpile", /* EQN_TOK_RPILE */
+	"cpile", /* EQN_TOK_CPILE */
+	"matrix", /* EQN_TOK_MATRIX */
+	"ccol", /* EQN_TOK_CCOL */
+	"lcol", /* EQN_TOK_LCOL */
+	"rcol", /* EQN_TOK_RCOL */
+	"delim", /* EQN_TOK_DELIM */
+	"define", /* EQN_TOK_DEFINE */
+	"tdefine", /* EQN_TOK_TDEFINE */
+	"ndefine", /* EQN_TOK_NDEFINE */
+	"undef", /* EQN_TOK_UNDEF */
+	NULL, /* EQN_TOK_EOF */
+	"above", /* EQN_TOK_ABOVE */
 };
 
 enum	eqn_symt {
@@ -103,183 +200,73 @@ enum	eqn_symt {
 	EQNSYM__MAX
 };
 
-enum	eqnpartt {
-	EQN_DEFINE = 0,
-	EQN_NDEFINE,
-	EQN_TDEFINE,
-	EQN_SET,
-	EQN_UNDEF,
-	EQN_GFONT,
-	EQN_GSIZE,
-	EQN_BACK,
-	EQN_FWD,
-	EQN_UP,
-	EQN_DOWN,
-	EQN__MAX
-};
-
-struct	eqnstr {
-	const char	*name;
-	size_t		 sz;
-};
-
-#define	STRNEQ(p1, sz1, p2, sz2) \
-	((sz1) == (sz2) && 0 == strncmp((p1), (p2), (sz1)))
-#define	EQNSTREQ(x, p, sz) \
-	STRNEQ((x)->name, (x)->sz, (p), (sz))
-
-struct	eqnpart {
-	struct eqnstr	 str;
-	int		(*fp)(struct eqn_node *);
-};
-
 struct	eqnsym {
-	struct eqnstr	 str;
+	const char	*str;
 	const char	*sym;
 };
 
-static	enum eqn_rest	 eqn_box(struct eqn_node *, struct eqn_box *);
-static	struct eqn_box	*eqn_box_alloc(struct eqn_node *,
-				struct eqn_box *);
-static	void		 eqn_box_free(struct eqn_box *);
-static	struct eqn_def	*eqn_def_find(struct eqn_node *,
-				const char *, size_t);
-static	int		 eqn_do_gfont(struct eqn_node *);
-static	int		 eqn_do_gsize(struct eqn_node *);
-static	int		 eqn_do_define(struct eqn_node *);
-static	int		 eqn_do_ign1(struct eqn_node *);
-static	int		 eqn_do_ign2(struct eqn_node *);
-static	int		 eqn_do_tdefine(struct eqn_node *);
-static	int		 eqn_do_undef(struct eqn_node *);
-static	enum eqn_rest	 eqn_eqn(struct eqn_node *, struct eqn_box *);
-static	enum eqn_rest	 eqn_list(struct eqn_node *, struct eqn_box *);
-static	enum eqn_rest	 eqn_matrix(struct eqn_node *, struct eqn_box *);
-static	const char	*eqn_nexttok(struct eqn_node *, size_t *);
-static	const char	*eqn_nextrawtok(struct eqn_node *, size_t *);
-static	const char	*eqn_next(struct eqn_node *,
-				char, size_t *, int);
-static	void		 eqn_rewind(struct eqn_node *);
-
-static	const struct eqnpart eqnparts[EQN__MAX] = {
-	{ { "define", 6 }, eqn_do_define }, /* EQN_DEFINE */
-	{ { "ndefine", 7 }, eqn_do_define }, /* EQN_NDEFINE */
-	{ { "tdefine", 7 }, eqn_do_tdefine }, /* EQN_TDEFINE */
-	{ { "set", 3 }, eqn_do_ign2 }, /* EQN_SET */
-	{ { "undef", 5 }, eqn_do_undef }, /* EQN_UNDEF */
-	{ { "gfont", 5 }, eqn_do_gfont }, /* EQN_GFONT */
-	{ { "gsize", 5 }, eqn_do_gsize }, /* EQN_GSIZE */
-	{ { "back", 4 }, eqn_do_ign1 }, /* EQN_BACK */
-	{ { "fwd", 3 }, eqn_do_ign1 }, /* EQN_FWD */
-	{ { "up", 2 }, eqn_do_ign1 }, /* EQN_UP */
-	{ { "down", 4 }, eqn_do_ign1 }, /* EQN_DOWN */
-};
-
-static	const struct eqnstr eqnmarks[EQNMARK__MAX] = {
-	{ "", 0 }, /* EQNMARK_NONE */
-	{ "dot", 3 }, /* EQNMARK_DOT */
-	{ "dotdot", 6 }, /* EQNMARK_DOTDOT */
-	{ "hat", 3 }, /* EQNMARK_HAT */
-	{ "tilde", 5 }, /* EQNMARK_TILDE */
-	{ "vec", 3 }, /* EQNMARK_VEC */
-	{ "dyad", 4 }, /* EQNMARK_DYAD */
-	{ "bar", 3 }, /* EQNMARK_BAR */
-	{ "under", 5 }, /* EQNMARK_UNDER */
-};
-
-static	const struct eqnstr eqnfonts[EQNFONT__MAX] = {
-	{ "", 0 }, /* EQNFONT_NONE */
-	{ "roman", 5 }, /* EQNFONT_ROMAN */
-	{ "bold", 4 }, /* EQNFONT_BOLD */
-	{ "fat", 3 }, /* EQNFONT_FAT */
-	{ "italic", 6 }, /* EQNFONT_ITALIC */
-};
-
-static	const struct eqnstr eqnposs[EQNPOS__MAX] = {
-	{ NULL, 0 }, /* EQNPOS_NONE */
-	{ "over", 4 }, /* EQNPOS_OVER */
-	{ "sup", 3 }, /* EQNPOS_SUP */
-	{ NULL, 0 }, /* EQNPOS_SUPSUB */
-	{ "sub", 3 }, /* EQNPOS_SUB */
-	{ "to", 2 }, /* EQNPOS_TO */
-	{ "from", 4 }, /* EQNPOS_FROM */
-	{ NULL, 0 }, /* EQNPOS_FROMTO */
-};
-
-static	const struct eqnstr eqnpiles[EQNPILE__MAX] = {
-	{ "", 0 }, /* EQNPILE_NONE */
-	{ "pile", 4 }, /* EQNPILE_PILE */
-	{ "cpile", 5 }, /* EQNPILE_CPILE */
-	{ "rpile", 5 }, /* EQNPILE_RPILE */
-	{ "lpile", 5 }, /* EQNPILE_LPILE */
-	{ "col", 3 }, /* EQNPILE_COL */
-	{ "ccol", 4 }, /* EQNPILE_CCOL */
-	{ "rcol", 4 }, /* EQNPILE_RCOL */
-	{ "lcol", 4 }, /* EQNPILE_LCOL */
-};
-
 static	const struct eqnsym eqnsyms[EQNSYM__MAX] = {
-	{ { "alpha", 5 }, "*a" }, /* EQNSYM_alpha */
-	{ { "beta", 4 }, "*b" }, /* EQNSYM_beta */
-	{ { "chi", 3 }, "*x" }, /* EQNSYM_chi */
-	{ { "delta", 5 }, "*d" }, /* EQNSYM_delta */
-	{ { "epsilon", 7 }, "*e" }, /* EQNSYM_epsilon */
-	{ { "eta", 3 }, "*y" }, /* EQNSYM_eta */
-	{ { "gamma", 5 }, "*g" }, /* EQNSYM_gamma */
-	{ { "iota", 4 }, "*i" }, /* EQNSYM_iota */
-	{ { "kappa", 5 }, "*k" }, /* EQNSYM_kappa */
-	{ { "lambda", 6 }, "*l" }, /* EQNSYM_lambda */
-	{ { "mu", 2 }, "*m" }, /* EQNSYM_mu */
-	{ { "nu", 2 }, "*n" }, /* EQNSYM_nu */
-	{ { "omega", 5 }, "*w" }, /* EQNSYM_omega */
-	{ { "omicron", 7 }, "*o" }, /* EQNSYM_omicron */
-	{ { "phi", 3 }, "*f" }, /* EQNSYM_phi */
-	{ { "pi", 2 }, "*p" }, /* EQNSYM_pi */
-	{ { "psi", 2 }, "*q" }, /* EQNSYM_psi */
-	{ { "rho", 3 }, "*r" }, /* EQNSYM_rho */
-	{ { "sigma", 5 }, "*s" }, /* EQNSYM_sigma */
-	{ { "tau", 3 }, "*t" }, /* EQNSYM_tau */
-	{ { "theta", 5 }, "*h" }, /* EQNSYM_theta */
-	{ { "upsilon", 7 }, "*u" }, /* EQNSYM_upsilon */
-	{ { "xi", 2 }, "*c" }, /* EQNSYM_xi */
-	{ { "zeta", 4 }, "*z" }, /* EQNSYM_zeta */
-	{ { "DELTA", 5 }, "*D" }, /* EQNSYM_DELTA */
-	{ { "GAMMA", 5 }, "*G" }, /* EQNSYM_GAMMA */
-	{ { "LAMBDA", 6 }, "*L" }, /* EQNSYM_LAMBDA */
-	{ { "OMEGA", 5 }, "*W" }, /* EQNSYM_OMEGA */
-	{ { "PHI", 3 }, "*F" }, /* EQNSYM_PHI */
-	{ { "PI", 2 }, "*P" }, /* EQNSYM_PI */
-	{ { "PSI", 3 }, "*Q" }, /* EQNSYM_PSI */
-	{ { "SIGMA", 5 }, "*S" }, /* EQNSYM_SIGMA */
-	{ { "THETA", 5 }, "*H" }, /* EQNSYM_THETA */
-	{ { "UPSILON", 7 }, "*U" }, /* EQNSYM_UPSILON */
-	{ { "XI", 2 }, "*C" }, /* EQNSYM_XI */
-	{ { "inter", 5 }, "ca" }, /* EQNSYM_inter */
-	{ { "union", 5 }, "cu" }, /* EQNSYM_union */
-	{ { "prod", 4 }, "product" }, /* EQNSYM_prod */
-	{ { "int", 3 }, "integral" }, /* EQNSYM_int */
-	{ { "sum", 3 }, "sum" }, /* EQNSYM_sum */
-	{ { "grad", 4 }, "gr" }, /* EQNSYM_grad */
-	{ { "del", 3 }, "gr" }, /* EQNSYM_del */
-	{ { "times", 5 }, "mu" }, /* EQNSYM_times */
-	{ { "cdot", 4 }, "pc" }, /* EQNSYM_cdot */
-	{ { "nothing", 7 }, "&" }, /* EQNSYM_nothing */
-	{ { "approx", 6 }, "~~" }, /* EQNSYM_approx */
-	{ { "prime", 5 }, "aq" }, /* EQNSYM_prime */
-	{ { "half", 4 }, "12" }, /* EQNSYM_half */
-	{ { "partial", 7 }, "pd" }, /* EQNSYM_partial */
-	{ { "inf", 3 }, "if" }, /* EQNSYM_inf */
-	{ { ">>", 2 }, ">>" }, /* EQNSYM_muchgreat */
-	{ { "<<", 2 }, "<<" }, /* EQNSYM_muchless */
-	{ { "<-", 2 }, "<-" }, /* EQNSYM_larrow */
-	{ { "->", 2 }, "->" }, /* EQNSYM_rarrow */
-	{ { "+-", 2 }, "+-" }, /* EQNSYM_pm */
-	{ { "!=", 2 }, "!=" }, /* EQNSYM_nequal */
-	{ { "==", 2 }, "==" }, /* EQNSYM_equiv */
-	{ { "<=", 2 }, "<=" }, /* EQNSYM_lessequal */
-	{ { ">=", 2 }, ">=" }, /* EQNSYM_moreequal */
+	{ "alpha", "*a" }, /* EQNSYM_alpha */
+	{ "beta", "*b" }, /* EQNSYM_beta */
+	{ "chi", "*x" }, /* EQNSYM_chi */
+	{ "delta", "*d" }, /* EQNSYM_delta */
+	{ "epsilon", "*e" }, /* EQNSYM_epsilon */
+	{ "eta", "*y" }, /* EQNSYM_eta */
+	{ "gamma", "*g" }, /* EQNSYM_gamma */
+	{ "iota", "*i" }, /* EQNSYM_iota */
+	{ "kappa", "*k" }, /* EQNSYM_kappa */
+	{ "lambda", "*l" }, /* EQNSYM_lambda */
+	{ "mu", "*m" }, /* EQNSYM_mu */
+	{ "nu", "*n" }, /* EQNSYM_nu */
+	{ "omega", "*w" }, /* EQNSYM_omega */
+	{ "omicron", "*o" }, /* EQNSYM_omicron */
+	{ "phi", "*f" }, /* EQNSYM_phi */
+	{ "pi", "*p" }, /* EQNSYM_pi */
+	{ "psi", "*q" }, /* EQNSYM_psi */
+	{ "rho", "*r" }, /* EQNSYM_rho */
+	{ "sigma", "*s" }, /* EQNSYM_sigma */
+	{ "tau", "*t" }, /* EQNSYM_tau */
+	{ "theta", "*h" }, /* EQNSYM_theta */
+	{ "upsilon", "*u" }, /* EQNSYM_upsilon */
+	{ "xi", "*c" }, /* EQNSYM_xi */
+	{ "zeta", "*z" }, /* EQNSYM_zeta */
+	{ "DELTA", "*D" }, /* EQNSYM_DELTA */
+	{ "GAMMA", "*G" }, /* EQNSYM_GAMMA */
+	{ "LAMBDA", "*L" }, /* EQNSYM_LAMBDA */
+	{ "OMEGA", "*W" }, /* EQNSYM_OMEGA */
+	{ "PHI", "*F" }, /* EQNSYM_PHI */
+	{ "PI", "*P" }, /* EQNSYM_PI */
+	{ "PSI", "*Q" }, /* EQNSYM_PSI */
+	{ "SIGMA", "*S" }, /* EQNSYM_SIGMA */
+	{ "THETA", "*H" }, /* EQNSYM_THETA */
+	{ "UPSILON", "*U" }, /* EQNSYM_UPSILON */
+	{ "XI", "*C" }, /* EQNSYM_XI */
+	{ "inter", "ca" }, /* EQNSYM_inter */
+	{ "union", "cu" }, /* EQNSYM_union */
+	{ "prod", "product" }, /* EQNSYM_prod */
+	{ "int", "integral" }, /* EQNSYM_int */
+	{ "sum", "sum" }, /* EQNSYM_sum */
+	{ "grad", "gr" }, /* EQNSYM_grad */
+	{ "del", "gr" }, /* EQNSYM_del */
+	{ "times", "mu" }, /* EQNSYM_times */
+	{ "cdot", "pc" }, /* EQNSYM_cdot */
+	{ "nothing", "&" }, /* EQNSYM_nothing */
+	{ "approx", "~~" }, /* EQNSYM_approx */
+	{ "prime", "aq" }, /* EQNSYM_prime */
+	{ "half", "12" }, /* EQNSYM_half */
+	{ "partial", "pd" }, /* EQNSYM_partial */
+	{ "inf", "if" }, /* EQNSYM_inf */
+	{ ">>", ">>" }, /* EQNSYM_muchgreat */
+	{ "<<", "<<" }, /* EQNSYM_muchless */
+	{ "<-", "<-" }, /* EQNSYM_larrow */
+	{ "->", "->" }, /* EQNSYM_rarrow */
+	{ "+-", "+-" }, /* EQNSYM_pm */
+	{ "!=", "!=" }, /* EQNSYM_nequal */
+	{ "==", "==" }, /* EQNSYM_equiv */
+	{ "<=", "<=" }, /* EQNSYM_lessequal */
+	{ ">=", ">=" }, /* EQNSYM_moreequal */
 };
 
-
 enum rofferr
 eqn_read(struct eqn_node **epp, int ln,
 		const char *p, int pos, int *offs)
@@ -353,386 +340,27 @@ eqn_alloc(const char *name, int pos, int line, struct mparse *parse)
 	return(p);
 }
 
-enum rofferr
-eqn_end(struct eqn_node **epp)
-{
-	struct eqn_node	*ep;
-	struct eqn_box	*root;
-	enum eqn_rest	 c;
-
-	ep = *epp;
-	*epp = NULL;
-
-	ep->eqn.root = mandoc_calloc(1, sizeof(struct eqn_box));
-
-	root = ep->eqn.root;
-	root->type = EQN_ROOT;
-
-	if (0 == ep->sz)
-		return(ROFF_IGN);
-
-	if (EQN_DESCOPE == (c = eqn_eqn(ep, root))) {
-		EQN_MSG(MANDOCERR_EQNNSCOPE, ep);
-		c = EQN_ERR;
-	}
-
-	return(EQN_EOF == c ? ROFF_EQN : ROFF_IGN);
-}
-
-static enum eqn_rest
-eqn_eqn(struct eqn_node *ep, struct eqn_box *last)
-{
-	struct eqn_box	*bp;
-	enum eqn_rest	 c;
-
-	bp = eqn_box_alloc(ep, last);
-	bp->type = EQN_SUBEXPR;
-
-	while (EQN_OK == (c = eqn_box(ep, bp)))
-		/* Spin! */ ;
-
-	return(c);
-}
-
-static enum eqn_rest
-eqn_matrix(struct eqn_node *ep, struct eqn_box *last)
-{
-	struct eqn_box	*bp;
-	const char	*start;
-	size_t		 sz;
-	enum eqn_rest	 c;
-
-	bp = eqn_box_alloc(ep, last);
-	bp->type = EQN_MATRIX;
-
-	if (NULL == (start = eqn_nexttok(ep, &sz))) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(EQN_ERR);
-	}
-	if ( ! STRNEQ(start, sz, "{", 1)) {
-		EQN_MSG(MANDOCERR_EQNSYNT, ep);
-		return(EQN_ERR);
-	}
-
-	while (EQN_OK == (c = eqn_box(ep, bp)))
-		switch (bp->last->pile) {
-		case EQNPILE_LCOL:
-			/* FALLTHROUGH */
-		case EQNPILE_CCOL:
-			/* FALLTHROUGH */
-		case EQNPILE_RCOL:
-			continue;
-		default:
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(EQN_ERR);
-		};
-
-	if (EQN_DESCOPE != c) {
-		if (EQN_EOF == c)
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(EQN_ERR);
-	}
-
-	eqn_rewind(ep);
-	start = eqn_nexttok(ep, &sz);
-	assert(start);
-	if (STRNEQ(start, sz, "}", 1))
-		return(EQN_OK);
-
-	EQN_MSG(MANDOCERR_EQNBADSCOPE, ep);
-	return(EQN_ERR);
-}
-
-static enum eqn_rest
-eqn_list(struct eqn_node *ep, struct eqn_box *last)
-{
-	struct eqn_box	*bp;
-	const char	*start;
-	size_t		 sz;
-	enum eqn_rest	 c;
-
-	bp = eqn_box_alloc(ep, last);
-	bp->type = EQN_LIST;
-
-	if (NULL == (start = eqn_nexttok(ep, &sz))) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(EQN_ERR);
-	}
-	if ( ! STRNEQ(start, sz, "{", 1)) {
-		EQN_MSG(MANDOCERR_EQNSYNT, ep);
-		return(EQN_ERR);
-	}
-
-	while (EQN_DESCOPE == (c = eqn_eqn(ep, bp))) {
-		eqn_rewind(ep);
-		start = eqn_nexttok(ep, &sz);
-		assert(start);
-		if ( ! STRNEQ(start, sz, "above", 5))
-			break;
-	}
-
-	if (EQN_DESCOPE != c) {
-		if (EQN_ERR != c)
-			EQN_MSG(MANDOCERR_EQNSCOPE, ep);
-		return(EQN_ERR);
-	}
-
-	eqn_rewind(ep);
-	start = eqn_nexttok(ep, &sz);
-	assert(start);
-	if (STRNEQ(start, sz, "}", 1))
-		return(EQN_OK);
-
-	EQN_MSG(MANDOCERR_EQNBADSCOPE, ep);
-	return(EQN_ERR);
-}
-
-static enum eqn_rest
-eqn_box(struct eqn_node *ep, struct eqn_box *last)
-{
-	size_t		 sz;
-	const char	*start;
-	char		*left;
-	char		 sym[64];
-	enum eqn_rest	 c;
-	int		 i, size;
-	struct eqn_box	*bp;
-
-	if (NULL == (start = eqn_nexttok(ep, &sz)))
-		return(EQN_EOF);
-
-	if (STRNEQ(start, sz, "}", 1))
-		return(EQN_DESCOPE);
-	else if (STRNEQ(start, sz, "right", 5))
-		return(EQN_DESCOPE);
-	else if (STRNEQ(start, sz, "above", 5))
-		return(EQN_DESCOPE);
-	else if (STRNEQ(start, sz, "mark", 4))
-		return(EQN_OK);
-	else if (STRNEQ(start, sz, "lineup", 6))
-		return(EQN_OK);
-
-	for (i = 0; i < (int)EQN__MAX; i++) {
-		if ( ! EQNSTREQ(&eqnparts[i].str, start, sz))
-			continue;
-		return((*eqnparts[i].fp)(ep) ? EQN_OK : EQN_ERR);
-	}
-
-	if (STRNEQ(start, sz, "{", 1)) {
-		if (EQN_DESCOPE != (c = eqn_eqn(ep, last))) {
-			if (EQN_ERR != c)
-				EQN_MSG(MANDOCERR_EQNSCOPE, ep);
-			return(EQN_ERR);
-		}
-		eqn_rewind(ep);
-		start = eqn_nexttok(ep, &sz);
-		assert(start);
-		if (STRNEQ(start, sz, "}", 1))
-			return(EQN_OK);
-		EQN_MSG(MANDOCERR_EQNBADSCOPE, ep);
-		return(EQN_ERR);
-	}
-
-	for (i = 0; i < (int)EQNPILE__MAX; i++) {
-		if ( ! EQNSTREQ(&eqnpiles[i], start, sz))
-			continue;
-		if (EQN_OK == (c = eqn_list(ep, last)))
-			last->last->pile = (enum eqn_pilet)i;
-		return(c);
-	}
-
-	if (STRNEQ(start, sz, "matrix", 6))
-		return(eqn_matrix(ep, last));
-
-	if (STRNEQ(start, sz, "left", 4)) {
-		if (NULL == (start = eqn_nexttok(ep, &sz))) {
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-			return(EQN_ERR);
-		}
-		left = mandoc_strndup(start, sz);
-		c = eqn_eqn(ep, last);
-		if (last->last)
-			last->last->left = left;
-		else
-			free(left);
-		if (EQN_DESCOPE != c)
-			return(c);
-		assert(last->last);
-		eqn_rewind(ep);
-		start = eqn_nexttok(ep, &sz);
-		assert(start);
-		if ( ! STRNEQ(start, sz, "right", 5))
-			return(EQN_DESCOPE);
-		if (NULL == (start = eqn_nexttok(ep, &sz))) {
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-			return(EQN_ERR);
-		}
-		last->last->right = mandoc_strndup(start, sz);
-		return(EQN_OK);
-	}
-
-	/*
-	 * Positional elements (e.g., over, sub, sup, ...).
-	 */
-	for (i = 0; i < (int)EQNPOS__MAX; i++) {
-		/* Some elements don't have names (are virtual). */
-		if (NULL == eqnposs[i].name)
-			continue;
-		else if ( ! EQNSTREQ(&eqnposs[i], start, sz))
-			continue;
-		if (NULL == last->last) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(EQN_ERR);
-		}
-		/*
-		 * If we encounter x sub y sup z, then according to the
-		 * eqn manual, we regard this as x subsup y z.
-		 */
-		if (EQNPOS_SUP == i &&
-			NULL != last->last->prev &&
-			EQNPOS_SUB == last->last->prev->pos)
-			last->last->prev->pos = EQNPOS_SUBSUP;
-		else if (EQNPOS_TO == i &&
-			NULL != last->last->prev &&
-			EQNPOS_FROM == last->last->prev->pos)
-			last->last->prev->pos = EQNPOS_FROMTO;
-		else
-			last->last->pos = (enum eqn_post)i;
-
-		if (EQN_EOF == (c = eqn_box(ep, last))) {
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-			return(EQN_ERR);
-		}
-		return(c);
-	}
-
-	for (i = 0; i < (int)EQNMARK__MAX; i++) {
-		if ( ! EQNSTREQ(&eqnmarks[i], start, sz))
-			continue;
-		if (NULL == last->last) {
-			EQN_MSG(MANDOCERR_EQNSYNT, ep);
-			return(EQN_ERR);
-		}
-		last->last->mark = (enum eqn_markt)i;
-		if (EQN_EOF == (c = eqn_box(ep, last))) {
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-			return(EQN_ERR);
-		}
-		return(c);
-	}
-
-	for (i = 0; i < (int)EQNFONT__MAX; i++) {
-		if ( ! EQNSTREQ(&eqnfonts[i], start, sz))
-			continue;
-		if (EQN_EOF == (c = eqn_box(ep, last))) {
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-			return(EQN_ERR);
-		} else if (EQN_OK == c)
-			last->last->font = (enum eqn_fontt)i;
-		return(c);
-	}
-
-	if (STRNEQ(start, sz, "size", 4)) {
-		if (NULL == (start = eqn_nexttok(ep, &sz))) {
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-			return(EQN_ERR);
-		}
-		size = mandoc_strntoi(start, sz, 10);
-		if (EQN_EOF == (c = eqn_box(ep, last))) {
-			EQN_MSG(MANDOCERR_EQNEOF, ep);
-			return(EQN_ERR);
-		} else if (EQN_OK != c)
-			return(c);
-		last->last->size = size;
-	}
-
-	bp = eqn_box_alloc(ep, last);
-	bp->type = EQN_TEXT;
-	for (i = 0; i < (int)EQNSYM__MAX; i++)
-		if (EQNSTREQ(&eqnsyms[i].str, start, sz)) {
-			sym[63] = '\0';
-			(void)snprintf(sym, 62, "\\[%s]", eqnsyms[i].sym);
-			bp->text = mandoc_strdup(sym);
-			return(EQN_OK);
-		}
-
-	bp->text = mandoc_strndup(start, sz);
-	return(EQN_OK);
-}
-
-void
-eqn_free(struct eqn_node *p)
+/*
+ * Find the key "key" of the give size within our eqn-defined values.
+ */
+static struct eqn_def *
+eqn_def_find(struct eqn_node *ep, const char *key, size_t sz)
 {
 	int		 i;
 
-	eqn_box_free(p->eqn.root);
-
-	for (i = 0; i < (int)p->defsz; i++) {
-		free(p->defs[i].key);
-		free(p->defs[i].val);
-	}
-
-	free(p->eqn.name);
-	free(p->data);
-	free(p->defs);
-	free(p);
-}
-
-static struct eqn_box *
-eqn_box_alloc(struct eqn_node *ep, struct eqn_box *parent)
-{
-	struct eqn_box	*bp;
-
-	bp = mandoc_calloc(1, sizeof(struct eqn_box));
-	bp->parent = parent;
-	bp->size = ep->gsize;
-
-	if (NULL != parent->first) {
-		parent->last->next = bp;
-		bp->prev = parent->last;
-	} else
-		parent->first = bp;
-
-	parent->last = bp;
-	return(bp);
-}
-
-static void
-eqn_box_free(struct eqn_box *bp)
-{
-
-	if (bp->first)
-		eqn_box_free(bp->first);
-	if (bp->next)
-		eqn_box_free(bp->next);
-
-	free(bp->text);
-	free(bp->left);
-	free(bp->right);
-	free(bp);
-}
-
-static const char *
-eqn_nextrawtok(struct eqn_node *ep, size_t *sz)
-{
-
-	return(eqn_next(ep, '"', sz, 0));
-}
-
-static const char *
-eqn_nexttok(struct eqn_node *ep, size_t *sz)
-{
-
-	return(eqn_next(ep, '"', sz, 1));
-}
-
-static void
-eqn_rewind(struct eqn_node *ep)
-{
+	for (i = 0; i < (int)ep->defsz; i++)
+		if (ep->defs[i].keysz && STRNEQ(ep->defs[i].key,
+		    ep->defs[i].keysz, key, sz))
+			return(&ep->defs[i]);
 
-	ep->cur = ep->rew;
+	return(NULL);
 }
 
+/*
+ * Get the next token from the input stream using the given quote
+ * character.
+ * Optionally make any replacements.
+ */
 static const char *
 eqn_next(struct eqn_node *ep, char quote, size_t *sz, int repl)
 {
@@ -822,48 +450,157 @@ again:
 	return(start);
 }
 
-static int
-eqn_do_ign1(struct eqn_node *ep)
+/*
+ * Get the next delimited token using the default current quote
+ * character.
+ */
+static const char *
+eqn_nexttok(struct eqn_node *ep, size_t *sz)
 {
 
-	if (NULL == eqn_nextrawtok(ep, NULL))
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-	else
-		return(1);
+	return(eqn_next(ep, '"', sz, 1));
+}
+
+/*
+ * Get next token without replacement.
+ */
+static const char *
+eqn_nextrawtok(struct eqn_node *ep, size_t *sz)
+{
 
-	return(0);
+	return(eqn_next(ep, '"', sz, 0));
 }
 
-static int
-eqn_do_ign2(struct eqn_node *ep)
+/*
+ * Parse a token from the stream of text.
+ * A token consists of one of the recognised eqn(7) strings.
+ * Strings are separated by delimiting marks.
+ * This returns EQN_TOK_EOF when there are no more tokens.
+ * If the token is an unrecognised string literal, then it returns
+ * EQN_TOK__MAX and sets the "p" pointer to an allocated, nil-terminated
+ * string.
+ * This must be later freed with free(3).
+ */
+static enum eqn_tok
+eqn_tok_parse(struct eqn_node *ep, char **p)
 {
+	const char	*start;
+	size_t		 i, sz;
 
-	if (NULL == eqn_nextrawtok(ep, NULL))
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-	else if (NULL == eqn_nextrawtok(ep, NULL))
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-	else
-		return(1);
+	if (NULL != p)
+		*p = NULL;
+
+	if (NULL == (start = eqn_nexttok(ep, &sz)))
+		return(EQN_TOK_EOF);
+
+	for (i = 0; i < EQN_TOK__MAX; i++) {
+		if (NULL == eqn_toks[i])
+			continue;
+		if (STRNEQ(start, sz, eqn_toks[i], strlen(eqn_toks[i])))
+			break;
+	}
+
+	if (i == EQN_TOK__MAX && NULL != p)
+		*p = mandoc_strndup(start, sz);
+
+	return(i);
+}
+
+static void
+eqn_box_free(struct eqn_box *bp)
+{
 
-	return(0);
+	if (bp->first)
+		eqn_box_free(bp->first);
+	if (bp->next)
+		eqn_box_free(bp->next);
+
+	free(bp->text);
+	free(bp->left);
+	free(bp->right);
+	free(bp->top);
+	free(bp->bottom);
+	free(bp);
 }
 
+/*
+ * Allocate a box as the last child of the parent node.
+ */
+static struct eqn_box *
+eqn_box_alloc(struct eqn_node *ep, struct eqn_box *parent)
+{
+	struct eqn_box	*bp;
+
+	bp = mandoc_calloc(1, sizeof(struct eqn_box));
+	bp->parent = parent;
+	bp->parent->args++;
+	bp->expectargs = UINT_MAX;
+	bp->size = ep->gsize;
+
+	assert(NULL != parent);
+
+	if (NULL != parent->first) {
+		assert(NULL != parent->last);
+		parent->last->next = bp;
+		bp->prev = parent->last;
+	} else
+		parent->first = bp;
+
+	parent->last = bp;
+	return(bp);
+}
+
+/*
+ * Reparent the current last node (of the current parent) under a new
+ * EQN_SUBEXPR as the first element.
+ * Then return the new parent.
+ * The new EQN_SUBEXPR will have a two-child limit.
+ */
+static struct eqn_box *
+eqn_box_makebinary(struct eqn_node *ep, 
+	enum eqn_post pos, struct eqn_box *parent)
+{
+	struct eqn_box	*b, *newb;
+
+	assert(NULL != parent->last);
+	b = parent->last;
+	if (parent->last == parent->first)
+		parent->first = NULL;
+	parent->args--;
+	parent->last = b->prev;
+	b->prev = NULL;
+	newb = eqn_box_alloc(ep, parent);
+	newb->pos = pos;
+	newb->type = EQN_SUBEXPR;
+	newb->expectargs = 2;
+	newb->args = 1;
+	newb->first = newb->last = b;
+	newb->first->next = NULL;
+	b->parent = newb;
+	return(newb);
+}
+
+/*
+ * Undefine a previously-defined string.
+ */
 static int
-eqn_do_tdefine(struct eqn_node *ep)
+eqn_undef(struct eqn_node *ep)
 {
+	const char	*start;
+	struct eqn_def	*def;
+	size_t		 sz;
 
-	if (NULL == eqn_nextrawtok(ep, NULL))
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-	else if (NULL == eqn_next(ep, ep->data[(int)ep->cur], NULL, 0))
+	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
 		EQN_MSG(MANDOCERR_EQNEOF, ep);
-	else
-		return(1);
+		return(0);
+	} else if (NULL != (def = eqn_def_find(ep, start, sz)))
+		def->keysz = 0;
 
-	return(0);
+	return(1);
 }
 
 static int
-eqn_do_define(struct eqn_node *ep)
+eqn_def(struct eqn_node *ep)
 {
 	const char	*start;
 	size_t		 sz;
@@ -879,7 +616,6 @@ eqn_do_define(struct eqn_node *ep)
 	 * Search for a key that already exists.
 	 * Create a new key if none is found.
 	 */
-
 	if (NULL == (def = eqn_def_find(ep, start, sz))) {
 		/* Find holes in string array. */
 		for (i = 0; i < (int)ep->defsz; i++)
@@ -906,7 +642,7 @@ eqn_do_define(struct eqn_node *ep)
 
 	if (NULL == start) {
 		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(0);
+		return(-1);
 	}
 
 	def->valsz = sz;
@@ -916,56 +652,449 @@ eqn_do_define(struct eqn_node *ep)
 	return(1);
 }
 
+/*
+ * Recursively parse an eqn(7) expression.
+ */
 static int
-eqn_do_gfont(struct eqn_node *ep)
-{
-
-	if (NULL == eqn_nextrawtok(ep, NULL)) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(0);
-	}
-	return(1);
-}
-
-static int
-eqn_do_gsize(struct eqn_node *ep)
+eqn_parse(struct eqn_node *ep, struct eqn_box *parent)
 {
+	char		*p;
+	enum eqn_tok	 tok;
+	enum eqn_post	 pos;
+	struct eqn_box	*cur;
+	int		 rc, size;
+	size_t		 i, sz;
+	char		 sym[64];
 	const char	*start;
-	size_t		 sz;
 
-	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
+	assert(NULL != parent);
+again:
+	
+	switch ((tok = eqn_tok_parse(ep, &p))) {
+	case (EQN_TOK_UNDEF):
+		if ((rc = eqn_undef(ep)) <= 0)
+			return(rc);
+		break;
+	case (EQN_TOK_NDEFINE):
+	case (EQN_TOK_DEFINE):
+		if ((rc = eqn_def(ep)) <= 0)
+			return(rc);
+		break;
+	case (EQN_TOK_TDEFINE):
+		if (NULL == eqn_nextrawtok(ep, NULL))
+			EQN_MSG(MANDOCERR_EQNEOF, ep);
+		else if (NULL == eqn_next(ep, 
+				ep->data[(int)ep->cur], NULL, 0))
+			EQN_MSG(MANDOCERR_EQNEOF, ep);
+		break;
+	case (EQN_TOK_GFONT):
+		if (NULL == eqn_nextrawtok(ep, NULL)) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		break;
+	case (EQN_TOK_MARK):
+	case (EQN_TOK_LINEUP):
+		/* Ignore these. */
+		break;
+	case (EQN_TOK_DYAD):
+	case (EQN_TOK_VEC):
+	case (EQN_TOK_UNDER):
+	case (EQN_TOK_BAR):
+	case (EQN_TOK_TILDE):
+	case (EQN_TOK_HAT):
+	case (EQN_TOK_DOT):
+	case (EQN_TOK_DOTDOT):
+		if (NULL == parent->last) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		parent = eqn_box_makebinary
+			(ep, EQNPOS_NONE, parent);
+		parent->type = EQN_LISTONE;
+		parent->expectargs = 1;
+		switch (tok) {
+		case (EQN_TOK_DOTDOT):
+			strlcpy(sym, "\\[ad]", sizeof(sym));
+			break;
+		case (EQN_TOK_VEC):
+			strlcpy(sym, "\\[->]", sizeof(sym));
+			break;
+		case (EQN_TOK_DYAD):
+			strlcpy(sym, "\\[<>]", sizeof(sym));
+			break;
+		case (EQN_TOK_TILDE):
+			strlcpy(sym, "\\[a~]", sizeof(sym));
+			break;
+		case (EQN_TOK_UNDER):
+			strlcpy(sym, "\\[ul]", sizeof(sym));
+			break;
+		case (EQN_TOK_BAR):
+			strlcpy(sym, "\\[rl]", sizeof(sym));
+			break;
+		case (EQN_TOK_DOT):
+			strlcpy(sym, "\\[a.]", sizeof(sym));
+			break;
+		case (EQN_TOK_HAT):
+			strlcpy(sym, "\\[ha]", sizeof(sym));
+			break;
+		default:
+			abort();
+		}
+
+		switch (tok) {
+		case (EQN_TOK_DOTDOT):
+		case (EQN_TOK_VEC):
+		case (EQN_TOK_DYAD):
+		case (EQN_TOK_TILDE):
+		case (EQN_TOK_BAR):
+		case (EQN_TOK_DOT):
+		case (EQN_TOK_HAT):
+			parent->top = mandoc_strdup(sym);
+			break;
+		case (EQN_TOK_UNDER):
+			parent->bottom = mandoc_strdup(sym);
+			break;
+		default:
+			abort();
+		}
+		parent = parent->parent;
+		break;
+	case (EQN_TOK_FWD):
+	case (EQN_TOK_BACK):
+	case (EQN_TOK_DOWN):
+	case (EQN_TOK_UP):
+		tok = eqn_tok_parse(ep, NULL); 
+		if (EQN_TOK__MAX != tok) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		break;
+	case (EQN_TOK_FAT):
+	case (EQN_TOK_ROMAN):
+	case (EQN_TOK_ITALIC):
+	case (EQN_TOK_BOLD):
+		while (parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		/*
+		 * These values apply to the next word or sequence of
+		 * words; thus, we mark that we'll have a child with
+		 * exactly one of those.
+		 */
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_LISTONE;
+		parent->expectargs = 1;
+		switch (tok) {
+		case (EQN_TOK_FAT):
+			parent->font = EQNFONT_FAT;
+			break;
+		case (EQN_TOK_ROMAN):
+			parent->font = EQNFONT_ROMAN;
+			break;
+		case (EQN_TOK_ITALIC):
+			parent->font = EQNFONT_ITALIC;
+			break;
+		case (EQN_TOK_BOLD):
+			parent->font = EQNFONT_BOLD;
+			break;
+		default:
+			abort();
+		}
+		break;
+	case (EQN_TOK_SIZE):
+	case (EQN_TOK_GSIZE):
+		/* Accept two values: integral size and a single. */
+		if (NULL == (start = eqn_nexttok(ep, &sz))) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		size = mandoc_strntoi(start, sz, 10);
+		if (-1 == size) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		if (EQN_TOK_GSIZE == tok) {
+			ep->gsize = size;
+			break;
+		}
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_LISTONE;
+		parent->expectargs = 1;
+		parent->size = size;
+		break;
+	case (EQN_TOK_FROM):
+	case (EQN_TOK_TO):
+	case (EQN_TOK_SUB):
+	case (EQN_TOK_SUP):
+		/*
+		 * We have a left-right-associative expression.
+		 * Repivot under a positional node, open a child scope
+		 * and keep on reading.
+		 */
+		if (NULL == parent->last) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		/* Handle the "subsup" and "fromto" positions. */
+		if (EQN_TOK_SUP == tok && parent->pos == EQNPOS_SUB) {
+			parent->expectargs = 3;
+			parent->pos = EQNPOS_SUBSUP;
+			break;
+		}
+		if (EQN_TOK_TO == tok && parent->pos == EQNPOS_FROM) {
+			parent->expectargs = 3;
+			parent->pos = EQNPOS_FROMTO;
+			break;
+		}
+		switch (tok) {
+		case (EQN_TOK_FROM):
+			pos = EQNPOS_FROM;
+			break;
+		case (EQN_TOK_TO):
+			pos = EQNPOS_TO;
+			break;
+		case (EQN_TOK_SUP):
+			pos = EQNPOS_SUP;
+			break;
+		case (EQN_TOK_SUB):
+			pos = EQNPOS_SUB;
+			break;
+		default:
+			abort();
+		}
+		parent = eqn_box_makebinary(ep, pos, parent);
+		break;
+	case (EQN_TOK_SQRT):
+		while (parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		/* 
+		 * Accept a left-right-associative set of arguments just
+		 * like sub and sup and friends but without rebalancing
+		 * under a pivot.
+		 */
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_SUBEXPR;
+		parent->pos = EQNPOS_SQRT;
+		parent->expectargs = 1;
+		break;
+	case (EQN_TOK_OVER):
+		/*
+		 * We have a right-left-associative fraction.
+		 * Close out anything that's currently open, then
+		 * rebalance and continue reading.
+		 */
+		if (NULL == parent->last) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		while (EQN_SUBEXPR == parent->type)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		parent = eqn_box_makebinary(ep, EQNPOS_OVER, parent);
+		break;
+	case (EQN_TOK_RIGHT):
+	case (EQN_TOK_BRACE_CLOSE):
+		/*
+		 * Close out the existing brace.
+		 * FIXME: this is a shitty sentinel: we should really
+		 * have a native EQN_BRACE type or whatnot.
+		 */
+		while (parent->type != EQN_LIST) 
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		if (EQN_TOK_RIGHT == tok) {
+			if (NULL == parent->left) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+			if (NULL == (start = eqn_nexttok(ep, &sz))) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+			/* Handling depends on right/left. */
+			if (STRNEQ(start, sz, "ceiling", 7)) {
+				strlcpy(sym, "\\[rc]", sizeof(sym));
+				parent->right = mandoc_strdup(sym);
+			} else if (STRNEQ(start, sz, "floor", 5)) {
+				strlcpy(sym, "\\[rf]", sizeof(sym));
+				parent->right = mandoc_strdup(sym);
+			} else 
+				parent->right = mandoc_strndup(start, sz);
+		}
+		if (NULL == (parent = parent->parent)) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		if (EQN_TOK_BRACE_CLOSE == tok && parent && 
+			(parent->type == EQN_PILE ||
+			 parent->type == EQN_MATRIX))
+			parent = parent->parent;
+		/* Close out any "singleton" lists. */
+		while (parent->type == EQN_LISTONE && 
+			parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		break;
+	case (EQN_TOK_BRACE_OPEN):
+	case (EQN_TOK_LEFT):
+		/*
+		 * If we already have something in the stack and we're
+		 * in an expression, then rewind til we're not any more
+		 * (just like with the text node).
+		 */
+		while (parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_LIST;
+		if (EQN_TOK_LEFT == tok) {
+			if (NULL == (start = eqn_nexttok(ep, &sz))) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+			/* Handling depends on right/left. */
+			if (STRNEQ(start, sz, "ceiling", 7)) {
+				strlcpy(sym, "\\[lc]", sizeof(sym));
+				parent->left = mandoc_strdup(sym);
+			} else if (STRNEQ(start, sz, "floor", 5)) {
+				strlcpy(sym, "\\[lf]", sizeof(sym));
+				parent->left = mandoc_strdup(sym);
+			} else 
+				parent->left = mandoc_strndup(start, sz);
+		}
+		break;
+	case (EQN_TOK_PILE):
+	case (EQN_TOK_LPILE):
+	case (EQN_TOK_RPILE):
+	case (EQN_TOK_CPILE):
+	case (EQN_TOK_CCOL):
+	case (EQN_TOK_LCOL):
+	case (EQN_TOK_RCOL):
+		while (parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		if (EQN_TOK_BRACE_OPEN != eqn_tok_parse(ep, NULL)) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_PILE;
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_LIST;
+		break;
+	case (EQN_TOK_ABOVE):
+		while (parent->type != EQN_PILE) 
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_LIST;
+		break;
+	case (EQN_TOK_MATRIX):
+		while (parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		if (EQN_TOK_BRACE_OPEN != eqn_tok_parse(ep, NULL)) {
+			EQN_MSG(MANDOCERR_EQNSYNT, ep);
+			return(-1);
+		}
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_MATRIX;
+		parent = eqn_box_alloc(ep, parent);
+		parent->type = EQN_LIST;
+		break;
+	case (EQN_TOK_EOF):
+		/*
+		 * End of file! 
+		 * TODO: make sure we're not in an open subexpression.
+		 */
 		return(0);
+	default:
+		assert(tok == EQN_TOK__MAX);
+		assert(NULL != p);
+		/*
+		 * If we already have something in the stack and we're
+		 * in an expression, then rewind til we're not any more.
+		 */
+		while (parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				free(p);
+				return(-1);
+			}
+		cur = eqn_box_alloc(ep, parent);
+		cur->type = EQN_TEXT;
+		for (i = 0; i < EQNSYM__MAX; i++)
+			if (0 == strcmp(eqnsyms[i].str, p)) {
+				(void)snprintf(sym, sizeof(sym), 
+					"\\[%s]", eqnsyms[i].sym);
+				cur->text = mandoc_strdup(sym);
+				free(p);
+				break;
+			}
+
+		if (i == EQNSYM__MAX)
+			cur->text = p;
+		/*
+		 * Post-process list status.
+		 */
+		while (parent->type == EQN_LISTONE && 
+			parent->args == parent->expectargs)
+			if (NULL == (parent = parent->parent)) {
+				EQN_MSG(MANDOCERR_EQNSYNT, ep);
+				return(-1);
+			}
+		break;
 	}
-	ep->gsize = mandoc_strntoi(start, sz, 10);
-	return(1);
+	goto again;
 }
 
-static int
-eqn_do_undef(struct eqn_node *ep)
+enum rofferr
+eqn_end(struct eqn_node **epp) 
 {
-	const char	*start;
-	struct eqn_def	*def;
-	size_t		 sz;
+	struct eqn_node	*ep;
 
-	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
-		EQN_MSG(MANDOCERR_EQNEOF, ep);
-		return(0);
-	} else if (NULL != (def = eqn_def_find(ep, start, sz)))
-		def->keysz = 0;
+	ep = *epp;
+	*epp = NULL;
 
-	return(1);
+	ep->eqn.root = mandoc_calloc(1, sizeof(struct eqn_box));
+	ep->eqn.root->expectargs = UINT_MAX;
+	return(0 == eqn_parse(ep, ep->eqn.root) ? ROFF_EQN : ROFF_IGN);
 }
 
-static struct eqn_def *
-eqn_def_find(struct eqn_node *ep, const char *key, size_t sz)
+void
+eqn_free(struct eqn_node *p)
 {
 	int		 i;
 
-	for (i = 0; i < (int)ep->defsz; i++)
-		if (ep->defs[i].keysz && STRNEQ(ep->defs[i].key,
-		    ep->defs[i].keysz, key, sz))
-			return(&ep->defs[i]);
+	eqn_box_free(p->eqn.root);
 
-	return(NULL);
+	for (i = 0; i < (int)p->defsz; i++) {
+		free(p->defs[i].key);
+		free(p->defs[i].val);
+	}
+
+	free(p->eqn.name);
+	free(p->data);
+	free(p->defs);
+	free(p);
 }
diff --git a/eqn_html.c b/eqn_html.c
index f2e7f79d..73828684 100644
--- a/eqn_html.c
+++ b/eqn_html.c
@@ -1,4 +1,4 @@
-/*	$Id: eqn_html.c,v 1.7 2014/09/28 20:14:20 kristaps Exp $ */
+/*	$Id: eqn_html.c,v 1.8 2014/10/10 08:44:24 kristaps Exp $ */
 /*
  * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -27,90 +27,64 @@
 #include "out.h"
 #include "html.h"
 
-static	const enum htmltag fontmap[EQNFONT__MAX] = {
-	TAG_SPAN, /* EQNFONT_NONE */
-	TAG_SPAN, /* EQNFONT_ROMAN */
-	TAG_B, /* EQNFONT_BOLD */
-	TAG_B, /* EQNFONT_FAT */
-	TAG_I /* EQNFONT_ITALIC */
-};
-
-static const struct eqn_box *
-	eqn_box(struct html *, const struct eqn_box *, int);
-
-
-void
-print_eqn(struct html *p, const struct eqn *ep)
+static void
+eqn_box(struct html *p, const struct eqn_box *bp)
 {
-	struct htmlpair	 tag;
-	struct tag	*t;
-
-	PAIR_CLASS_INIT(&tag, "eqn");
-	t = print_otag(p, TAG_MATH, 1, &tag);
-
-	p->flags |= HTML_NONOSPACE;
-	eqn_box(p, ep->root, 1);
-	p->flags &= ~HTML_NONOSPACE;
-
-	print_tagq(p, t);
-}
-
-/*
- * This function is fairly brittle.
- * This is because the eqn syntax doesn't play so nicely with recusive
- * formats, e.g.,
- *     foo sub bar sub baz
- * ...needs to resolve into
- *     <msub> foo <msub> bar, baz </msub> </msub>
- * In other words, we need to embed some recursive work.
- * FIXME: this does NOT handle right-left associativity or precedence!
- */
-static const struct eqn_box *
-eqn_box(struct html *p, const struct eqn_box *bp, int next)
-{
-	struct tag	*post, *pilet, *tmp;
+	struct tag	*post, *row, *cell, *t;
 	struct htmlpair	 tag[2];
-	int		 skiptwo;
+	const struct eqn_box *child, *parent;
+	size_t		 i, j, rows;
 
 	if (NULL == bp)
-		return(NULL);
-
-	post = pilet = NULL;
-	skiptwo = 0;
+		return;
 
-	/*
-	 * If we're a "row" under a pile, then open up the piling
-	 * context here.
-	 * We do this first because the pile surrounds the content of
-	 * the contained expression.
-	 */
-	if (NULL != bp->parent && bp->parent->pile != EQNPILE_NONE) {
-		pilet = print_otag(p, TAG_MTR, 0, NULL);
-		print_otag(p, TAG_MTD, 0, NULL);
-	}
-	if (NULL != bp->parent && bp->parent->type == EQN_MATRIX) {
-		pilet = print_otag(p, TAG_MTABLE, 0, NULL);
-		print_otag(p, TAG_MTR, 0, NULL);
-		print_otag(p, TAG_MTD, 0, NULL);
-	}
+	post = NULL;
 
 	/*
-	 * If we're establishing a pile, start the table mode now.
-	 * If we've already in a pile row, then don't override "pilet",
-	 * because we'll be closed out anyway.
+	 * Special handling for a matrix, which is presented to us in
+	 * column order, but must be printed in row-order.
 	 */
-	if (bp->pile != EQNPILE_NONE) {
-		tmp = print_otag(p, TAG_MTABLE, 0, NULL);
-		pilet = (NULL == pilet) ? tmp : pilet;
+	if (EQN_MATRIX == bp->type) {
+		if (NULL == bp->first)
+			goto out;
+		assert(EQN_LIST == bp->first->type);
+		if (NULL == (parent = bp->first->first))
+			goto out;
+		assert(EQN_PILE == parent->type);
+		/* Estimate the number of rows, first. */
+		if (NULL == (child = parent->first))
+			goto out;
+		for (rows = 0; NULL != child; rows++) 
+			child = child->next;
+		/* Print row-by-row. */
+		post = print_otag(p, TAG_MTABLE, 0, NULL);
+		for (i = 0; i < rows; i++) {
+			parent = bp->first->first;
+			row = print_otag(p, TAG_MTR, 0, NULL);
+			while (NULL != parent) {
+				child = parent->first;
+				for (j = 0; j < i; j++) {
+					if (NULL == child)
+						break;
+					child = child->next;
+				}
+				cell = print_otag
+					(p, TAG_MTD, 0, NULL);
+				/* 
+				 * If we have no data for this
+				 * particular cell, then print a
+				 * placeholder and continue--don't puke.
+				 */
+				if (NULL != child) 
+					eqn_box(p, child->first);
+				print_tagq(p, cell);
+				parent = parent->next;
+			}
+			print_tagq(p, row);
+		}
+		goto out;
 	}
 
-	/*
-	 * Positioning.
-	 * This is the most complicated part, and actually doesn't quite
-	 * work (FIXME) because it doesn't account for associativity.
-	 * Setting "post" will mean that we're only going to process a
-	 * single or double following expression.
-	 */
 	switch (bp->pos) {
 	case (EQNPOS_TO):
 		post = print_otag(p, TAG_MOVER, 0, NULL);
@@ -129,93 +103,86 @@ eqn_box(struct html *p, const struct eqn_box *bp, int next)
 		break;
 	case (EQNPOS_FROMTO):
 		post = print_otag(p, TAG_MUNDEROVER, 0, NULL);
-		skiptwo = 1;
 		break;
 	case (EQNPOS_SUBSUP):
 		post = print_otag(p, TAG_MSUBSUP, 0, NULL);
-		skiptwo = 1;
+		break;
+	case (EQNPOS_SQRT):
+		post = print_otag(p, TAG_MSQRT, 0, NULL);
 		break;
 	default:
 		break;
 	}
 
-	/*t = EQNFONT_NONE == bp->font ? NULL :
-	    print_otag(p, fontmap[(int)bp->font], 0, NULL);*/
+	if (bp->top || bp->bottom) {
+		assert(NULL == post);
+		if (bp->top && NULL == bp->bottom)
+			post = print_otag(p, TAG_MOVER, 0, NULL);
+		else if (bp->top && bp->bottom)
+			post = print_otag(p, TAG_MUNDEROVER, 0, NULL);
+		else if (bp->bottom)
+			post = print_otag(p, TAG_MUNDER, 0, NULL);
+	}
+
+	if (EQN_PILE == bp->type) {
+		assert(NULL == post);
+		post = print_otag(p, TAG_MTABLE, 0, NULL);
+	} else if (bp->parent && EQN_PILE == bp->parent->type) {
+		assert(NULL == post);
+		post = print_otag(p, TAG_MTR, 0, NULL);
+		print_otag(p, TAG_MTD, 0, NULL);
+	}
 
 	if (NULL != bp->text) {
-		assert(NULL == bp->first);
-		/*
-		 * We have text.
-		 * This can be a number, a function, a variable, or
-		 * pretty much anything else.
-		 * First, check for some known functions.
-		 * If we're going to create a structural node (e.g.,
-		 * sqrt), then set the "post" variable only if it's not
-		 * already set.
-		 */
-		if (0 == strcmp(bp->text, "sqrt")) {
-			tmp = print_otag(p, TAG_MSQRT, 0, NULL);
-			post = (NULL == post) ? tmp : post;
-		} else if (0 == strcmp(bp->text, "+") ||
-			   0 == strcmp(bp->text, "-") ||
-			   0 == strcmp(bp->text, "=") ||
-			   0 == strcmp(bp->text, "(") ||
-			   0 == strcmp(bp->text, ")") ||
-			   0 == strcmp(bp->text, "/")) {
-			tmp = print_otag(p, TAG_MO, 0, NULL);
-			print_text(p, bp->text);
-			print_tagq(p, tmp);
-		} else {
-			tmp = print_otag(p, TAG_MI, 0, NULL);
-			print_text(p, bp->text);
-			print_tagq(p, tmp);
-		}
-	} else if (NULL != bp->first) {
-		assert(NULL == bp->text);
-		/* 
-		 * If we're a "fenced" component (i.e., having
-		 * brackets), then process those brackets now.
-		 * Otherwise, introduce a dummy row (if we're not
-		 * already in a table context).
-		 */
-		tmp = NULL;
+		assert(NULL == post);
+		post = print_otag(p, TAG_MI, 0, NULL);
+		print_text(p, bp->text);
+	} else if (NULL == post) { 
 		if (NULL != bp->left || NULL != bp->right) {
 			PAIR_INIT(&tag[0], ATTR_OPEN,
-				NULL != bp->left ? bp->left : "");
+				NULL == bp->left ? "" : bp->left);
 			PAIR_INIT(&tag[1], ATTR_CLOSE,
-				NULL != bp->right ? bp->right : "");
-			tmp = print_otag(p, TAG_MFENCED, 2, tag);
+				NULL == bp->right ? "" : bp->right);
+			post = print_otag(p, TAG_MFENCED, 2, tag);
+		} 
+		if (NULL == post)
+			post = print_otag(p, TAG_MROW, 0, NULL);
+		else
 			print_otag(p, TAG_MROW, 0, NULL);
-		} else if (NULL == pilet)
-			tmp = print_otag(p, TAG_MROW, 0, NULL);
-		eqn_box(p, bp->first, 1);
-		if (NULL != tmp)
-			print_tagq(p, tmp);
 	}
 
-	/*
-	 * If a positional context, invoke the "next" context.
-	 * This is recursive and will return the end of the recursive
-	 * chain of "next" contexts.
-	 */
-	if (NULL != post) {
-		bp = eqn_box(p, bp->next, 0);
-		if (skiptwo)
-			bp = eqn_box(p, bp->next, 0);
-		print_tagq(p, post);
+	eqn_box(p, bp->first);
+
+out:
+	if (NULL != bp->bottom) {
+		t = print_otag(p, TAG_MO, 0, NULL);
+		print_text(p, bp->bottom);
+		print_tagq(p, t);
+	} 
+	if (NULL != bp->top) {
+		t = print_otag(p, TAG_MO, 0, NULL);
+		print_text(p, bp->top);
+		print_tagq(p, t);
 	}
 
-	/* 
-	 * If we're being piled (either directly, in the table, or
-	 * indirectly in a table row), then close that out.
-	 */
-	if (NULL != pilet)
-		print_tagq(p, pilet);
+	if (NULL != post)
+		print_tagq(p, post);
 
-	/*
-	 * If we're normally processing, then grab the next node.
-	 * If we're in a recursive context, then don't seek to the next
-	 * node; further recursion has already been handled.
-	 */
-	return(next ? eqn_box(p, bp->next, 1) : bp);
+	eqn_box(p, bp->next);
+}
+
+void
+print_eqn(struct html *p, const struct eqn *ep)
+{
+	struct htmlpair	 tag;
+	struct tag	*t;
+
+	PAIR_CLASS_INIT(&tag, "eqn");
+	t = print_otag(p, TAG_MATH, 1, &tag);
+
+	p->flags |= HTML_NONOSPACE;
+	eqn_box(p, ep->root);
+	p->flags &= ~HTML_NONOSPACE;
+
+	print_tagq(p, t);
 }
diff --git a/html.c b/html.c
index 957c070b..e213bd51 100644
--- a/html.c
+++ b/html.c
@@ -1,4 +1,4 @@
-/*	$Id: html.c,v 1.174 2014/09/28 20:14:20 kristaps Exp $ */
+/*	$Id: html.c,v 1.175 2014/10/10 08:44:24 kristaps Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011, 2012, 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -105,6 +105,7 @@ static	const char	*const htmlattrs[ATTR_MAX] = {
 	"charset", /* ATTR_CHARSET */
 	"open", /* ATTR_OPEN */
 	"close", /* ATTR_CLOSE */
+	"mathvariant", /* ATTR_MATHVARIANT */
 };
 
 static	const char	*const roffscales[SCALE_MAX] = {
diff --git a/html.h b/html.h
index f3110eaf..78b42590 100644
--- a/html.h
+++ b/html.h
@@ -1,4 +1,4 @@
-/*	$Id: html.h,v 1.64 2014/09/28 20:14:20 kristaps Exp $ */
+/*	$Id: html.h,v 1.65 2014/10/10 08:44:24 kristaps Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -82,6 +82,7 @@ enum	htmlattr {
 	ATTR_CHARSET,
 	ATTR_OPEN,
 	ATTR_CLOSE,
+	ATTR_MATHVARIANT,
 	ATTR_MAX
 };
 
diff --git a/mandoc.1 b/mandoc.1
index 95f52689..e280a262 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -1,4 +1,4 @@
-.\"	$Id: mandoc.1,v 1.115 2014/10/07 14:07:03 schwarze Exp $
+.\"	$Id: mandoc.1,v 1.116 2014/10/10 08:44:24 kristaps Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2012, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: October 7 2014 $
+.Dd $Mdocdate: October 10 2014 $
 .Dt MANDOC 1
 .Os
 .Sh NAME
@@ -233,7 +233,7 @@ This is the default.
 See
 .Sx ASCII Output .
 .It Fl T Ns Cm html
-Produce CSS1/HTML5 output.
+Produce HTML5, CSS1, and MathML output.
 See
 .Sx HTML Output .
 .It Fl T Ns Cm lint
@@ -320,6 +320,10 @@ which will normalise to \(>=60.
 Output produced by
 .Fl T Ns Cm html
 conforms to HTML5 using optional self-closing tags.
+Default styles use only CSS1.
+Equations rendered from
+.Xr eqn 7
+blocks use MathML.
 .Pp
 The
 .Pa example.style.css
diff --git a/mandoc.h b/mandoc.h
index bf1c061b..ce673875 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -1,4 +1,4 @@
-/*	$Id: mandoc.h,v 1.158 2014/09/28 14:05:11 kristaps Exp $ */
+/*	$Id: mandoc.h,v 1.159 2014/10/10 08:44:24 kristaps Exp $ */
 /*
  * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -306,21 +306,10 @@ enum	eqn_boxt {
 	EQN_ROOT, /* root of parse tree */
 	EQN_TEXT, /* text (number, variable, whatever) */
 	EQN_SUBEXPR, /* nested `eqn' subexpression */
-	EQN_LIST, /* subexpressions list */
-	EQN_MATRIX /* matrix subexpression */
-};
-
-enum	eqn_markt {
-	EQNMARK_NONE = 0,
-	EQNMARK_DOT,
-	EQNMARK_DOTDOT,
-	EQNMARK_HAT,
-	EQNMARK_TILDE,
-	EQNMARK_VEC,
-	EQNMARK_DYAD,
-	EQNMARK_BAR,
-	EQNMARK_UNDER,
-	EQNMARK__MAX
+	EQN_LIST, /* list (braces, etc.) */
+	EQN_LISTONE, /* singleton list */
+	EQN_PILE, /* vertical pile */
+	EQN_MATRIX /* pile of piles */
 };
 
 enum	eqn_fontt {
@@ -334,13 +323,14 @@ enum	eqn_fontt {
 
 enum	eqn_post {
 	EQNPOS_NONE = 0,
-	EQNPOS_OVER,
 	EQNPOS_SUP,
 	EQNPOS_SUBSUP,
 	EQNPOS_SUB,
 	EQNPOS_TO,
 	EQNPOS_FROM,
 	EQNPOS_FROMTO,
+	EQNPOS_OVER,
+	EQNPOS_SQRT,
 	EQNPOS__MAX
 };
 
@@ -371,10 +361,13 @@ struct	eqn_box {
 	struct eqn_box	 *prev; /* node sibling */
 	struct eqn_box	 *parent; /* node sibling */
 	char		 *text; /* text (or NULL) */
-	char		 *left;
-	char		 *right;
+	char		 *left; /* fence left-hand */
+	char		 *right; /* fence right-hand */
+	char		 *top; /* expression over-symbol */
+	char		 *bottom; /* expression under-symbol */
+	size_t		  args; /* arguments in parent */
+	size_t		  expectargs; /* max arguments in parent */
 	enum eqn_post	  pos; /* position of next box */
-	enum eqn_markt	  mark; /* a mark about the box */
 	enum eqn_fontt	  font; /* font of box */
 	enum eqn_pilet	  pile; /* equation piling */
 };
diff --git a/tree.c b/tree.c
index 20386632..087ab55a 100644
--- a/tree.c
+++ b/tree.c
@@ -1,4 +1,4 @@
-/*	$Id: tree.c,v 1.55 2014/09/28 11:32:33 kristaps Exp $ */
+/*	$Id: tree.c,v 1.56 2014/10/10 08:44:24 kristaps Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -275,6 +275,7 @@ print_box(const struct eqn_box *ep, int indent)
 	case EQN_ROOT:
 		t = "eqn-root";
 		break;
+	case EQN_LISTONE:
 	case EQN_LIST:
 		t = "eqn-list";
 		break;
@@ -284,15 +285,19 @@ print_box(const struct eqn_box *ep, int indent)
 	case EQN_TEXT:
 		t = "eqn-text";
 		break;
+	case EQN_PILE:
+		t = "eqn-pile";
+		break;
 	case EQN_MATRIX:
 		t = "eqn-matrix";
 		break;
 	}
 
 	assert(t);
-	printf("%s(size=%d, pos=%d, font=%d, mark=%d, pile=%d, l=\"%s\", r=\"%s\") %s\n",
+	printf("%s(size=%d, args=%zu(%zu), pos=%d, font=%d, pile=%d, l=\"%s\", r=\"%s\") %s\n",
 	    t, EQN_DEFSIZE == ep->size ? 0 : ep->size,
-	    ep->pos, ep->font, ep->mark, ep->pile,
+	    ep->args, ep->expectargs,
+	    ep->pos, ep->font, ep->pile,
 	    ep->left ? ep->left : "",
 	    ep->right ? ep->right : "",
 	    ep->text ? ep->text : "");